Prerender: Stop creating PrerenderNoVarySearchHintCommitDeferringCondition for exact match cases

PrerenderNoVarySearchHintCommitDeferringCondition is created to wait for
the No-Vary-Search header during prerender activation.

Before this CL, the condition was always created when the No-Vary-Search
hint was specified in the rule set. However, this condition was not
necessary when the navigation matched a prerendered page as
UrlMatchType::kExact or kURLPredicateMatch that did not require the
No-Vary-Search header.

This CL avoids creating the condition in those cases. This does not
change functional behavior, as eventually the navigation will be
blocked by PrerenderCommitDeferringCondition until prerendering is
complete. But this avoids the case where the navigation can be blocked
twice that could affect navigation performance.

Bug: 356764567
Change-Id: I5560d4e4e50f150ae4783f35c7ed0615dab16cee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5799451
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Reviewed-by: Lingqi Chi <lingqi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1345204}