Don't build test dependencies for manual tests

The `code-owners-ts-tests` target is only used for tests that
themselves are not automatically run. Running `bazelisk build //...`
would still build that target, which is unnecessary.

Also currently the tests are broken and thus prevent builds,
if the exact target is not being selected.

Change-Id: I724ace09eaeda0211dcf87cfc5012d450416e111

web/BUILD

diff --git a/web/BUILD b/web/BUILD
index 24d4bcc..14f51e4 100644
--- a/web/BUILD
+++ b/web/BUILD
@@ -38,6 +38,7 @@
     incremental = True,
     out_dir = "_bazel_ts_out_tests",
     tsconfig = ":tsconfig",
+    tags = ["manual"],
     deps = [
         "//plugins:node_modules",
         "//polygerrit-ui:node_modules",