fix: avoid per-request String.format in context decorators (#6805)

[yykaue]

Fixes #6805.

Summary

• Precompute the default module names for the Divide and WebSocket context decorators.
• Remove per-request String.format calls from the request path.
• Add an assertion covering the default Divide module name.
• Preserve the existing module naming behavior.

Optional.orElse(...) evaluates its fallback value eagerly, so the previous String.format was executed on every request, even when metadata contained an application name. Using static constants avoids this unnecessary formatting and allocation.

@Aias00, could you please help review this PR when you have time? Thank you!

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