infra: enable introspector for Rust

[DavidKorczynski]

No description provided.

[DavidKorczynski]

/gcbrun trial_build.py rust --sanitizer introspector --fuzzing-engine libfuzzer

[DavidKorczynski]

Errors in the builds fail with:

Step #6: gcr.io/oss-fuzz-base/base-builder-swift-testing-rust-fi-int:latest
Finished Step #6
Step #1: CommandException: No URLs matched: gs://oss-fuzz-coverage/migtd/textcov_reports/20241216/*
Step #1: CommandException: 1 file/object could not be transferred.

This is in essence expected because it's a chicken-and-egg situation: we need this PR to enable uploading of textcov_reports:

oss-fuzz/infra/build/functions/build_and_run_coverage.py

Lines 203 to 218 in 57fe447

	if project.fuzzing_language in LANGUAGES_WITH_INTROSPECTOR_SUPPORT:
	# Upload the text coverage reports. Delete the old ones just in case.
	upload_textcov_reports_url = bucket.get_upload_url('textcov_reports')
	build_steps.append(build_lib.gsutil_rm_rf_step(upload_textcov_reports_url))
	build_steps.append({
	'name':
	'gcr.io/cloud-builders/gsutil',
	'args': [
	'-m',
	'cp',
	'-r',
	os.path.join(build.out, 'textcov_reports'),
	upload_textcov_reports_url,
	],

[DavidKorczynski]

/gcbrun trial_build.py all --sanitizer introspector --fuzzing-engine libfuzzer

[DavidKorczynski]

To solve the textcov_reports issue I'll allow failure on this step:

oss-fuzz/infra/build/functions/build_lib.py

Lines 274 to 279 in 57fe447

	coverage_data_path = os.path.join(f'{out_dir}/textcov_reports/')
	bucket_url = f'gs://{bucket_name}/{project_name}/textcov_reports/{latest}/*'
	steps.append({
	'name': 'gcr.io/cloud-builders/gsutil',
	'args': ['-m', 'cp', '-r', bucket_url, coverage_data_path]
	})

This code is only used by Fuzz Introspector runs and it's okay if it fails.

Will do it after the current trial build, since we still want to test the bumping of Fuzz Introspector and the changes applies are okay for non-rust projects.

[DavidKorczynski]

The latest trial build succeeds. The ones that fail are rust projects because of the textcov issues, which is also related to failing coverage builds.

[DavidKorczynski]

/gcbrun trial_build.py rust --sanitizer introspector --fuzzing-engine libfuzzer

[DavidKorczynski]

Looks good -- the few projects failing are due to build issues and not this PR.

This is good to go.