gh-130149: fix HMAC tests for some FIPS-only build bots

[picnixz]

I can just skip those tests on FIPS-only build bots. Currently, the Python implementation of HMAC was just delegating to any existing implementation, but some of them are not available at all (neither in OpenSSL nor as built-in modules).

So for now, Python implementation of HMAC is tested with OpenSSL hash functions instead.

• Issue: Refactor tests for HMAC #130149

[picnixz]

!buildbot FIPS

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @picnixz for commit cc2fbe1 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F130788%2Fmerge

The command will test the builders whose names match following regular expression: FIPS

The builders matched are:

• AMD64 RHEL8 FIPS Only Blake2 Builtin Hash PR
• AMD64 CentOS9 FIPS No Builtin Hashes PR
• AMD64 RHEL8 FIPS No Builtin Hashes PR
• AMD64 CentOS9 FIPS Only Blake2 Builtin Hash PR

[picnixz]

I'm pretty sure the tests will fail (because those build bots are already failing) but they shouldn't fail more

[picnixz]

So, the two failures are now back to what they were previously. Those two build bots were already failing but now test_hmac does not fail anymore on them.