PR503969: Make test results of make ltpchecks compatible with bunsen

PR503969: Make test results of make ltpchecks compatible with bunsen

Synthesize automake-like testcase log format for bunsen compatibility.

Each testcase now produces a triplet of <testcase>.{log,trs}, and a
test-suite.log file.  This way test results can be uploaded to bunsen
using the t-upload-git-push command.

The <testcase>.log file contains the actual testcase log. The .trs
file contains automake-encoded test result.  The test-suite.log
file contains testcase timing information.

The log directory tree respect the one of the LTP testcases to avoid
naming collisions.

Here is how the test result was uploaded to Bunsen:

> TESTING FINISHED, logs in /home/mcermak/WORK/valgrind/valgrind/auxprogs/auxchecks/ltp-full-20250130/ltp
> make[1]: Leaving directory '/home/mcermak/WORK/valgrind/valgrind/auxprogs'
>
> real	8m27.467s
> user	44m46.416s
> sys	6m46.405s
> 41$ cd /home/mcermak/WORK/valgrind/valgrind/auxprogs/auxchecks/ltp-full-20250130/ltp
> 41$ t-upload-git-push ssh://builder.sourceware.org/git/bunsendb.git mcermak/PR503969-$(date +%s) \
>  $(find . -type f -name '*.log' -o -name  '*.trs' -o -name 'test-suite.log')
> 3036eba2de1cc44a1942f9681720ea234da9029e refs/tags/mcermak/PR503969-1747389329
> 41$

Here's the resulting bunsen upload:
https://builder.sourceware.org/testrun/3036eba2de1cc44a1942f9681720ea234da9029e