Fix crashes in oracle provider when db workspace is set

[nyalldawson]

When a workspace was set, we were using a different connection ID string when creating a connection in the connection pool vs when we were destroying it. This triggered an assert, resulting in crashes when connections were invalidated.

[nyalldawson]

(This is NOT possible to unit test)

[github-actions]

🪟 Windows Qt6 builds

Download Windows Qt6 builds of this PR for testing.
(Built from commit 63224c2)

🪟 Windows builds

Download Windows builds of this PR for testing.
Debug symbols for this build are available here.
(Built from commit 63224c2)

[thbaumann]

I tested this pull request and it fixed the problem for me when connecting to oracle layers.

[troopa81]

Thanks!

[qgis-bot]

The backport to release-3_40 failed:

The process '/usr/bin/git' failed with exit code 1

stderr

error: could not apply 3643a2947f7... Add extra debugging for Oracle connections
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
hint: Disable this message with "git config set advice.mergeConflict false"

stdout

Auto-merging src/providers/oracle/qgsoracleconn.cpp
CONFLICT (content): Merge conflict in src/providers/oracle/qgsoracleconn.cpp

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-release-3_40 release-3_40
# Navigate to the new working tree
cd .worktrees/backport-release-3_40
# Create a new branch
git switch --create backport-60957-to-release-3_40
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick 3643a2947f731d1b146d01e7a75c9ac36c580e8f,63224c215195d670e2510cbf4cbadd0a5c627458
# Push it to GitHub
git push --set-upstream origin backport-60957-to-release-3_40
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release-3_40

Then, create a pull request where the base branch is release-3_40 and the compare/head branch is backport-60957-to-release-3_40.