added temporary default values for some flags.

There are TODOs to remove these defaults when they are
not needed but it makes running these command much easier
for the person handling the release.

Author: vimanyu

scripts/update_android_ios_dependencies.py

@@ -666,14 +666,19 @@ def parse_cmdline_args():
             help='Just print the replaced lines, DO NOT overwrite any files')
   parser.add_argument( "--log_level", default="info",
             help="Logging level (debug, warning, info)")
+  # TODO: remove default values when we decide to update androidx for 
+  # gameloop_android as well.
   parser.add_argument('--ignore_directories', nargs='+',
+            default=('gameloop_android', 'scripts'),
             help='Ignore updating any files in these directories (names).')
   parser.add_argument('--allow_experimental', action='store_true',
             help='Allow updating to experimental versions (eg:1.2.3-alpha))')
   # iOS options
   parser.add_argument('--skip_ios', action='store_true',
             help='Skip iOS pod version update completely.')
+  # TODO: remove default values when Ads SDK does not need to be pinned.
   parser.add_argument('--ignore_ios_pods', nargs='+',
+            default=('Google-Mobile-Ads-SDK',),
             help='Ignore iOS pods which have any of the items specified in '
                  'this list as substrings.')
   parser.add_argument('--podfiles', nargs='+', default=(os.getcwd(),),
@@ -683,7 +688,9 @@ def parse_cmdline_args():
   # Android options
   parser.add_argument('--skip_android', action='store_true',
             help='Skip Android libraries version update completely.')
+  # TODO: remove default values when Ads SDK does not need to be pinned.
   parser.add_argument('--ignore_android_packages', nargs='+',
+            default=('firebase-ads',),
             help='Ignore Android packages which have any of the items '
                  'specified in this list as substrings.')
   parser.add_argument('--depfiles', nargs='+',