Use the same exclusive lease key name for all indexing actions

What does this MR do and why?

Related to #386922 (closed)

Because the lease key was dependent on class names it was possible for indexing and reindexing actions to happen at the same time(on the same table) leading to deadlocks:

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.