mruby: fix run_tests.sh by upgrading to Ubuntu 24

[DavidKorczynski]

The goal of this PR is to improve the Chronos support for mruby. mruby has some failing tests on Ruby 2.7 which is what the Ubuntu 20 base image uses. Upgrading to Ubuntu 24 resolved this problem and consequently means we can remove the check for failing tests that we have:

python3 infra/helper.py check-tests mruby --integrity-check
...
Skip: Method call in rescue => backtrace isn't available (core)
  Total: 2049
     OK: 2028
     KO: 0
  Crash: 0
Warning: 2
   Skip: 19
   Time: 3.03 seconds

>>> Bintest host <<<
bintest - Command Binary Test

.........................................................................................................
  Total: 105
     OK: 105
     KO: 0
  Crash: 0
Warning: 0
   Skip: 0
   Time: 7.53 seconds
+ python3 /chronos/integrity_validator_run_tests.py diff-patch after

[JustinStitt]

I am just a passerby who ran into some problems with this tooling

How did the original PR #14172 land in this state when @oliverchang voiced their concerns regarding flaky magic numbers in two separate threads?

I think this PR description needs some more info about 1) what was wrong before, 2) what the fix is and 3) how it is more robust than before.

[DavidKorczynski]

How did the original PR #14172 land in this state when @oliverchang voiced their concerns regarding flaky magic numbers in two separate threads?

Probably for a variety of reasons. (1) no better solution at the time; (2) many projects were being handled then and many had subsets of tests not passing under oss-fuzz conditions so we came up with these types of solutions; (3) time pressure due to other tooling needed to experiment with the run_tests.sh; (4) the Chronos infra was still being developed so a lot was not set in stone IIRC, etc.

Chronos is not used by users really and it's not used by public processes, so it's not really obvious when things go wrong/if they do, at least not to us. @oliverchang may give some more insights as we were discussing things privately as well.

I think this PR description needs some more info about 1) what was wrong before, 2) what the fix is and 3) how it is more robust than before.

sounds good.

[DavidKorczynski]

note: it would be good to validate if we can avoid monitoring for crashing tests, but instead get the single failing test to work.

edit: we should be able to do that if we have Ruby 3.0 instead of Ruby 2.7.0 in the base image. Bumping to Ubuntu 24 may solve this

[DavidKorczynski]

This should be good now:

python3 infra/helper.py check-tests mruby --integrity-check
...
Skip: Method call in rescue => backtrace isn't available (core)
  Total: 2049
     OK: 2028
     KO: 0
  Crash: 0
Warning: 2
   Skip: 19
   Time: 3.03 seconds

>>> Bintest host <<<
bintest - Command Binary Test

.........................................................................................................
  Total: 105
     OK: 105
     KO: 0
  Crash: 0
Warning: 0
   Skip: 0
   Time: 7.53 seconds
+ python3 /chronos/integrity_validator_run_tests.py diff-patch after

[JustinStitt]

looks great!

[DavidKorczynski]

@JustinStitt let me know if you run into other issues with this or other Chronos integrations! I'll see if I can go through to find if there are other breakages atm.