Authentication mode set on tool does not get respected when it is added again to an agent (after being deleted previously in global auth enabled mode).

[sangee2004]

Steps to reproduce the problem

1. Create agent with tool - github using oauth as authentication mode.
2. Pre authenticate the tool.
3. Remove this tool.
4. Add github tool again this time choosing PAT

Tool will get added into pre authenticated mode ( User was not promoted for PAT tokens)

Removing tool is step 3 does not result in agent level credential for the tool to be removed.

Expected Behavior:
When tool is being added to an agent that already has credential set (like in step 4) , user should not be allowed to pick an oauth mode that is different from the credential that already exists.

Or we should be able to clear the existing agent credential and add the tool as being not in pre authenticated mode.