Assorted synth fixups / cleanups (#6400)

* Asset: Replace 'stable' -> 'latest' in docs links, caused by out-of-date synth.
* AutoML: fix copying generated docs.
* Bigtable: remove now-spurious fixup from 'synth.py'.
* DLP: remove now-spurious fixups from 'synth.py'.
* Monitoring: remove now-spurious fixups from 'synth.py'.
* Redis: remove now-spurious fixups from 'synth.py'.
* Speech: remove now-spurious fixups from 'synth.py'.

packages/google-cloud-speech/synth.py

@@ -40,20 +40,6 @@
 s.move(library / 'google/cloud/speech.py')
 
 
-# Fix bad reference to operations_v1
-s.replace(
-    '**/gapic/**/*_transport.py',
-    r' \= operations_v1\.',
-    ' = google.api_core.operations_v1.')
-
-
-# Fix bad docstrings.
-s.replace(
-    '**/gapic/*_client.py',
-    r'\\"(.+?)-\*\\"',
-    r'"\1-\\*"')
-
-
 # Issues exist where python files should define the source encoding
 # https://github.com/googleapis/gapic-generator/issues/2097
 s.replace(