[test] Move cctest/test-regexp to unittests

... /regexp/regexp-unittest.

Bug: v8:12781
Change-Id: I3c3ba4c519ff503b242c39d0e3b2350f25d7e84c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3607370Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: 王澳 <wangao.james@bytedance.com>
Cr-Commit-Position: refs/heads/main@{#80217}

test/cctest/BUILD.gn

@@ -242,7 +242,6 @@ v8_source_set("cctest_sources") {
     "test-property-details.cc",
     "test-ptr-compr-cage.cc",
     "test-random-number-generator.cc",
-    "test-regexp.cc",
     "test-representation.cc",
     "test-roots.cc",
     "test-sampler-api.cc",