Fix: don't forget diff= parameter while searching in diff mode

[psrok1]

Your checklist for this pull request

• I've read the contributing guideline.
• I've tested my changes by building and running the project, and testing changed functionality (if applicable)
• I've added automated tests for my change (if applicable, optional)
• I've updated documentation to reflect my change (if applicable)

What is the current behaviour?

When "Diff with.." option is used, MWDB UI escapes from diff mode into standard mode when we use Search. It happens because setSearchParams forget about diff= argument in query parameters.

What is the new behaviour?

Fixed setSearchParams invocation to not lose other arguments while updating search params

Test plan

Closing issues