Remove old libfuzzer dotnet template (#2875)

### Context
The original `libfuzzer dotnet` job template was a proof of concept that demonstrated how the `libfuzzer_fuzz` task could be used to express fuzzing via the (pre SharpFuzz 2.0) `libfuzzer-dotnet` tool. It (and its associated integration test) used a harness that linked an older version of SharpFuzz, and which is incompatible with LibFuzzerDotnetLoader (which requires SharpFuzz 2.0 or greater).

### Changes
- Rename `libfuzzer dotnet_dll` job template to `libfuzzer dotnet`, making it the _only_ `libfuzzer-dotnet` template
- Remove integration tests and docs for the old proof-of-concept job type

### Notice

This is a breaking change.

Closes #2874.

src/cli/onefuzz/templates/libfuzzer.py

@@ -568,138 +568,6 @@ class Libfuzzer(Command):
         return helper.job
 
     def dotnet(
-        self,
-        project: str,
-        name: str,
-        build: str,
-        pool_name: PoolName,
-        *,
-        setup_dir: Directory,
-        target_harness: str,
-        vm_count: int = 1,
-        inputs: Optional[Directory] = None,
-        reboot_after_setup: bool = False,
-        duration: int = 24,
-        target_workers: Optional[int] = None,
-        target_options: Optional[List[str]] = None,
-        fuzzing_target_options: Optional[List[str]] = None,
-        target_env: Optional[Dict[str, str]] = None,
-        tags: Optional[Dict[str, str]] = None,
-        wait_for_running: bool = False,
-        wait_for_files: Optional[List[ContainerType]] = None,
-        existing_inputs: Optional[Container] = None,
-        readonly_inputs: Optional[Container] = None,
-        debug: Optional[List[TaskDebugFlag]] = None,
-        ensemble_sync_delay: Optional[int] = None,
-        check_fuzzer_help: bool = True,
-        expect_crash_on_failure: bool = False,
-        notification_config: Optional[NotificationConfig] = None,
-    ) -> Optional[Job]:
-        """
-        libfuzzer-dotnet task
-        """
-
-        # ensure containers exist
-        if existing_inputs:
-            self.onefuzz.containers.get(existing_inputs)
-
-        if readonly_inputs:
-            self.onefuzz.containers.get(readonly_inputs)
-
-        harness = "libfuzzer-dotnet"
-
-        pool = self.onefuzz.pools.get(pool_name)
-        if pool.os != OS.linux:
-            raise Exception("libfuzzer-dotnet jobs are only compatible on linux")
-
-        target_exe = File(os.path.join(setup_dir, harness))
-        if not os.path.exists(target_exe):
-            raise Exception(f"missing harness: {target_exe}")
-
-        assembly_path = os.path.join(setup_dir, target_harness)
-        if not os.path.exists(assembly_path):
-            raise Exception(f"missing assembly: {target_harness}")
-
-        self._check_is_libfuzzer(target_exe)
-        if target_options is None:
-            target_options = []
-        target_options = [
-            "--target_path={setup_dir}/" + "{target_harness}"
-        ] + target_options
-
-        helper = JobHelper(
-            self.onefuzz,
-            self.logger,
-            project,
-            name,
-            build,
-            duration,
-            pool_name=pool_name,
-            target_exe=target_exe,
-        )
-
-        helper.add_tags(tags)
-        helper.define_containers(
-            ContainerType.setup,
-            ContainerType.inputs,
-            ContainerType.crashes,
-        )
-
-        if existing_inputs:
-            helper.containers[ContainerType.inputs] = existing_inputs
-        else:
-            helper.define_containers(ContainerType.inputs)
-
-        if readonly_inputs:
-            helper.containers[ContainerType.readonly_inputs] = readonly_inputs
-
-        fuzzer_containers = [
-            (ContainerType.setup, helper.containers[ContainerType.setup]),
-            (ContainerType.crashes, helper.containers[ContainerType.crashes]),
-            (ContainerType.inputs, helper.containers[ContainerType.inputs]),
-        ]
-
-        helper.create_containers()
-        helper.setup_notifications(notification_config)
-
-        helper.upload_setup(setup_dir, target_exe)
-        if inputs:
-            helper.upload_inputs(inputs)
-        helper.wait_on(wait_for_files, wait_for_running)
-
-        # Build `target_options` for the `libfuzzer_fuzz` task.
-        #
-        # This allows passing arguments like `-runs` to the target only when
-        # invoked in persistent fuzzing mode, and not test case repro mode.
-        libfuzzer_fuzz_target_options = target_options.copy()
-
-        if fuzzing_target_options:
-            libfuzzer_fuzz_target_options += fuzzing_target_options
-
-        self.onefuzz.tasks.create(
-            helper.job.job_id,
-            TaskType.libfuzzer_fuzz,
-            harness,
-            fuzzer_containers,
-            pool_name=pool_name,
-            reboot_after_setup=reboot_after_setup,
-            duration=duration,
-            vm_count=vm_count,
-            target_options=libfuzzer_fuzz_target_options,
-            target_env=target_env,
-            target_workers=target_workers,
-            tags=tags,
-            debug=debug,
-            ensemble_sync_delay=ensemble_sync_delay,
-            check_fuzzer_help=check_fuzzer_help,
-            expect_crash_on_failure=expect_crash_on_failure,
-        )
-
-        self.logger.info("done creating tasks")
-        helper.wait()
-        return helper.job
-
-    def dotnet_dll(
         self,
         project: str,
         name: str,