t: add test for git refs optimize subcommand

Add a test script, `t/t1463-refs-optimize.sh`, for the new `git refs
optimize` command.

This script acts as a simple driver, leveraging the shared test library
created in the preceding commit. It works by overriding the
`$pack_refs` variable to "refs optimize" and then sourcing the
shared library (`t/pack-refs-tests.sh`).

This approach ensures that `git refs optimize` is tested against the
entire comprehensive test suite of `git pack-refs`, verifying
that it acts as a compatible drop-in replacement.

Mentored-by: Patrick Steinhardt <ps@pks.im>
Mentored-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Meet Soni <meetsoni3017@gmail.com>

Author: inosmeet

t/meson.build

@@ -213,6 +213,7 @@ integration_tests = [
   't1460-refs-migrate.sh',
   't1461-refs-list.sh',
   't1462-refs-exists.sh',
+  't1463-refs-optimize.sh',
   't1500-rev-parse.sh',
   't1501-work-tree.sh',
   't1502-rev-parse-parseopt.sh',

t/t1463-refs-optimize.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+test_description='git refs optimize should not change the branch semantic
+
+This test runs git refs optimize and git show-ref and checks that the branch
+semantic is still the same.
+'
+
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+GIT_TEST_DEFAULT_REF_FORMAT=files
+export GIT_TEST_DEFAULT_REF_FORMAT
+
+. ./test-lib.sh
+
+pack_refs='refs optimize'
+. "$TEST_DIRECTORY"/pack-refs-tests.sh