Move registerHooks to onExtensionRegistration to prevent logspam

[Sophivorus]

See https://github.com/SemanticMediaWiki/SemanticResultFormats/issues/794

[codecov-commenter]

Codecov Report

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

Comparison is base (8eb978e) 40.10% compared to head (088aa77) 40.10%. Report is 1 commits behind head on master.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #805 +/- ## ========================================= Coverage 40.10% 40.10% Complexity 2332 2332 ========================================= Files 78 78 Lines 8248 8248 ========================================= Hits 3308 3308 Misses 4940 4940 ```

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