Fix Gradle publish failure in FIPS mode

What does this MR do and why?

Previously in FIPS mode when a Gradle build attempted to publish a package with an MD5 checksum, GitLab Rails would return a 422 error. This only showed up as a warning with Maven, but Gradle fails the publish step entirely.

In FIPS mode, we've already told Workhorse not to generate a MD5 checksum via UploadHashFunctions, and the first FIPS check in the PUT request ensures that Workhorse obeys that. However, there was a second check in the PUT request that rejects the .md5 suffix, but this is unnecessary since no MD5 checksum will be stored. extract_format is a shared helper, make this second FIPS check optional since we still want to reject GET requests with the .md5 suffix.

Relates to #436387 (closed)

How to set up and validate locally

1. Check out the master branch.
2. Set FIPS_MODE=1 in the environment (e.g. env.runit).
3. gdk restart rails
4. In your GitLab instance, import the project with URL https://gitlab.com/gitlab-com/support/toolbox/gitlab-smoke-tests.
5. Click on Build -> Pipeline -> Run pipeline -> click on sh-support-gradle (gitlab-com/support/toolbox/gitlab-smoke-tests!29 (merged)).
6. Cancel all builds and retry maven-repository:gradle.
7. The build should fail with a 422 Unprocessible Entity error.
8. Repeat the test with this branch.