Update CI workflows to run a single test suite on each host instead of one test per host

[chatton]

Summary

Can be done after #6634

Once the above issue is done, we can update our CI workflows to specify a single test suite instead of a single test.

Note: there might be a few PRs for this issue. The following should be able to be done separately.

• modify the build_test_matrix.go script
• modify run-e2e.sh to enable both the new and already existing functionality (done in Enable Parallel Transfer Test Suite #6721)
• modify CI files to use the updated scripts and provide the correct matrices in the workflows.
• Migrate all test suites to use the new approach to run a full test suite. Enable Remainder of E2E tests to use t.Parallel() #6764
• Migrate fork workflows to use test suites

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For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged/assigned