Fix position info for equality expr errors

[FliegendeWurst]

Intended Change

This PR fixes the position info of the error for incorrect equality expressions.

Type of pull request

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] Refactoring (behaviour should not change or only minimally change)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] There are changes to the (Java) code
• [ ] There are changes to the taclet rule base
• [ ] There are changes to the deployment/CI infrastructure (gradle, github, ...)
• [ ] Other:

Ensuring quality

• [ ] I made sure that introduced/changed code is well documented (javadoc and inline comments).
• [ ] I made sure that new/changed end-user features are well documented (https://github.com/KeYProject/key-docs).
• [x] I added new test case(s) for new functionality: I re-enabled the test case by no longer marking it as broken
• [x] I have tested the feature as follows: automated test
• [ ] I have checked that runtime performance has not deteriorated.

Additional information and contact(s)

The contributions within this pull request are licensed under GPLv2 (only) for inclusion in KeY.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (1fb0c10) 37.77% compared to head (0e66dd9) 37.77%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #3429 +/- ## ========================================= Coverage 37.77% 37.77% - Complexity 17031 17036 +5 ========================================= Files 2076 2076 Lines 126950 126951 +1 Branches 21381 21381 ========================================= + Hits 47952 47962 +10 + Misses 73092 73084 -8 + Partials 5906 5905 -1 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.