Do not generate plugins doc cache by default

This is just a tracker bug to check all MR to stop building plugins doc cache by default.

mentioned in commit thiblahute/gst-build@48c14673

mentioned in commit thiblahute/gst-build@2c50c067

mentioned in commit thiblahute/gstreamer@96b1b99a

mentioned in commit thiblahute/gst-plugins-base@b26ae29c

mentioned in commit thiblahute/gst-plugins-good@350b6df4

mentioned in commit thiblahute/gst-plugins-ugly@b081d5a3

mentioned in commit thiblahute/gst-plugins-bad@c25d1105

mentioned in commit thiblahute/gst-editing-services@87d83c8c

mentioned in commit thiblahute/gst-libav@e3e99ddf

mentioned in commit thiblahute/gstreamer-vaapi@c2416dfc

mentioned in commit thiblahute/gst-rtsp-server@3cc3d352

mentioned in commit thiblahute/gst-rtsp-server@ef88a273

mentioned in commit thiblahute/gstreamer-vaapi@893aea9d

mentioned in merge request gst-rtsp-server!36 (merged)

mentioned in merge request gstreamer-vaapi!92 (merged)

mentioned in merge request gst-libav!26 (merged)

mentioned in merge request gst-editing-services!75 (merged)

mentioned in merge request gst-plugins-ugly!22 (merged)

mentioned in merge request gst-plugins-good!202 (merged)

mentioned in merge request gst-plugins-base!239 (merged)

mentioned in merge request gstreamer!155 (merged)

mentioned in commit thiblahute/gstreamer@e11e9903

mentioned in merge request gst-build!52 (merged)

mentioned in commit thiblahute/gst-docs@4a44f037

mentioned in merge request !46 (merged)

mentioned in commit thiblahute/gstreamer@0faab7d9

mentioned in merge request gst-plugins-bad!342 (merged)

closed via commit gst-plugins-base@b26ae29c

mentioned in commit thiblahute/gstreamer-vaapi@879e1081

mentioned in commit thiblahute/gst-editing-services@c83d8838

mentioned in commit tpm/gst-plugins-base@4a89608f

mentioned in merge request gst-plugins-base!245 (merged)