Remove trivial cases of unreachable code

Summary:
Static code analysis can detect Unreachable statement - code above always terminates.
The vast majority of occurrences in the Phorge codebase are due to an unreachable break within a case after a return or after an all-covering if/else.
All this noise makes it harder to spot real logic issues (there are some!), thus fix these trivial cases.

Test Plan: Examine the code; run static code analysis.

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed Committers, valerio.bozzolan

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25802