Remove --experimental-fs-watcher flag.

# Delete this line to force CI to run the JVM tests.
[ci skip-jvm-tests]
# Delete this line to force CI to run Clippy and the Rust tests.
[ci skip-rust-tests]

src/python/pants/option/global_options.py

@@ -865,16 +865,6 @@ def register_bootstrap_options(cls, register):
             help="Whether or not to use nailgun to run the requests that are marked as nailgunnable.",
             advanced=True,
         )
-        register(
-            "--experimental-fs-watcher",
-            type=bool,
-            default=True,
-            advanced=True,
-            removal_version="1.30.0.dev0",
-            removal_hint="Enabled by default: flag is disabled.",
-            help="Whether to use the engine filesystem watcher which registers the workspace"
-            " for kernel file change events",
-        )
 
     @classmethod
     def register_options(cls, register):