Fix many issues in gdal algs...

[nyalldawson]

Unit tests weren't running on the new CI structure, so these all slipped in 😭

[github-actions]

The backport to release-3_16 failed:

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

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_16 release-3_16
# Navigate to the new working tree
cd .worktrees/backport-release-3_16
# Create a new branch
git switch --create backport-41847-to-release-3_16
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 fe566bcc091aecc0270fc0202a61b744d7c2981b
# Push it to GitHub
git push --set-upstream origin backport-41847-to-release-3_16
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release-3_16

Then, create a pull request where the base branch is release-3_16 and the compare/head branch is backport-41847-to-release-3_16.

[github-actions]

The backport to release-3_18 failed:

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

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_18 release-3_18
# Navigate to the new working tree
cd .worktrees/backport-release-3_18
# Create a new branch
git switch --create backport-41847-to-release-3_18
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 fe566bcc091aecc0270fc0202a61b744d7c2981b
# Push it to GitHub
git push --set-upstream origin backport-41847-to-release-3_18
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release-3_18

Then, create a pull request where the base branch is release-3_18 and the compare/head branch is backport-41847-to-release-3_18.

[agiudiceandrea]

@nyalldawson the backport to 3.16 branch failed, but some of the issues fixed by this PR affect also 3.16.4, at least #41839 (fixed by "[processing][gdal] Fix escaping of connection string in OGR to postgis alg") and the issue fixed by "[processing] Fix escaping of srcnodata argument in Build Virtual Raster alg"

[nyalldawson]

@agiudiceandrea can you open the backport with them? I'll happily review..