pkg/obfuscate: replace double quoted strings after !=, <= and >= by question marks

[bwoebi]

What does this PR do?

Extending the amount of cases where double quoted strings are treated as real to be filtered strings to not only include = (see ba8253ee1b0272ca56fe1985f67e45abd803ed05), but also !=, <= and >=.

Motivation

We have a customer having a very large cardinality due to him comparing dates enclosed in double quoted strings.

Possible Drawbacks / Trade-offs

I'm not sure about possible overeager replacing with question marks where column names were meant, but given that it works with =, these new cases should be fine too, I assume.

Describe how to test/QA your changes

Added a simple test using these operators with double quoted strings.

[bits-bot]

All committers have signed the CLA.