git: re-enable a few tests that are fixed upstream

- t5150: now has the proper perl prerequisite check:
  https://git.kernel.org/pub/scm/git/git.git/tree/t/t5150-request-pull.sh?h=v2.43.0#n10
- t5319: flake was fixed:
  https://git.kernel.org/pub/scm/git/git.git/commit/?id=152923b132d57e1dbd693a8cb9a8bc1827405674
- t1700: no idea what did the fix, but it is working again

pkgs/applications/version-management/git/default.nix

@@ -325,8 +325,11 @@ stdenv.mkDerivation (finalAttrs: {
     substituteInPlace t/test-lib.sh \
       --replace "test_set_prereq POSIXPERM" ""
     # TODO: Investigate while these still fail (without POSIXPERM):
+    # Tested to fail: 2.46.0
     disable_test t0001-init 'shared overrides system'
+    # Tested to fail: 2.46.0
     disable_test t0001-init 'init honors global core.sharedRepository'
+    # Tested to fail: 2.46.0
     disable_test t1301-shared-repo
     # /build/git-2.44.0/contrib/completion/git-completion.bash: line 452: compgen: command not found
     disable_test t9902-completion
@@ -337,24 +340,12 @@ stdenv.mkDerivation (finalAttrs: {
     # Disable sendmail tests
     disable_test t9001-send-email
   '' + ''
-    # XXX: I failed to understand why this one fails.
-    # Could someone try to re-enable it on the next release ?
-    # Tested to fail: 2.18.0 and 2.19.0
-    disable_test t1700-split-index "null sha1"
-
     # Flaky tests:
-    disable_test t5319-multi-pack-index
     disable_test t6421-merge-partial-clone
 
     # Fails reproducibly on ZFS on Linux with formD normalization
     disable_test t0021-conversion
     disable_test t3910-mac-os-precompose
-
-  '' + lib.optionalString (!perlSupport) ''
-    # request-pull is a Bash script that invokes Perl, so it is not available
-    # when NO_PERL=1, and the test should be skipped, but the test suite does
-    # not check for the Perl prerequisite.
-    disable_test t5150-request-pull
   '' + lib.optionalString stdenv.isDarwin ''
     # XXX: Some tests added in 2.24.0 fail.
     # Please try to re-enable on the next release.