Re-enable Amazon Linux 2 CI build and test jobs

[stmontgomery]

Description

We recently added CI jobs to build and test this project on Amazon Linux 2 in in #1322. That helped us validate the fix for a build failure affecting that platform, but later we discovered runtime test failures and had to revert the new CI job in #1324.

This issue tracks eventually re-enabling this CI job and fix the test failures so we can begin regularly testing it.

Additional information

No response

[grynspan]

Looks like AL2 doesn't like exit tests and gets signal 4 (SIGILL?) for all of them, so we'll need to figure out what causes that.

Also a couple of smaller test failures, but nothing particularly vexing.