In #64024 , we changed our test setup for FIPS 140 to always use the default distribution because we always wanted to set xpack.security.fips_mode.enabled: true and we can't do this with INTEG_TEST distribution as in tests for non-xpack modules, that setting is not available.

We should try to refrain from setting a specific distribution in fips and use INTEG_TEST as much as possible ( to the extent that the test suites themselves already use it). This has two benefits:

• Improves cacheability and allows us to have a smaller footprint for our test clusters
• Most importantly, it allows us to have similar setups for fips and non-fips CI testing, which would alleviate most of the issues highlighted by the flakiness of Netty4HeadBodyIsEmptyIT.testTemplateExists fails in fips mode #66820

This issue is for tracking the problem so that we can schedule for the appropriate time for investigation and come up with a proposal on how to do this.