ci(*-leaks): skip the git-svn tests to save time

I noticed recently that the leak-checking jobs still take a lot of time, and upon analysis, the git-svn tests contribute significantly to this. Analyzing a recent CI run, I saw that the Git test suite contains 1,017 tests, running for approximately 5¼ hours total. Of these, 65 git-svn-related tests (~6% of test count) took 42.24 minutes combined, accounting for ~13.% of the total runtime. This implies that the git-svn tests are roughly twice as expernsive compared to the other tests. However, testing git-svn in the leak-checking jobs provides minimal value: git-svn is implemented as a Perl script, and leak checking only handles C code. While git-svn does call into Git's built-in commands that are implemented in C, these are standard Git operations that are already thoroughly exercised elsewhere in the test suite. Therefore, running the git-svn tests in the leak-checking jobs only adds to the overall run time with little value in return. Given that the leak-checking jobs are particularly time-intensive and these 42+ minutes of SVN tests per job provide no additional leak detection value, skip them in the *-leaks jobs to reduce CI runtime. Assisted-by: Claude Sonnet 4.5 Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>