Fix HTML-limited bot matching in prerender bypass rules (#96584)
## Summary
- preserve `htmlLimitedBots` substring semantics when generating the PPR
cache-bypass user-agent rule
- allow surrounding user-agent text so bots such as `googleweblight`
correctly bypass the prerender shell
- add deployment coverage confirming blocking metadata for bot
identifiers embedded in full user-agent strings, including custom
`htmlLimitedBots` patterns
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