Remove feature flag for conan package revisions support

What does this MR do and why?

The feature flag was globally enabled on gitlab.com on 2025-08-05 #483634 (comment 2670317370). So far, no errors were observed #483634 (comment 2674233442). Thus we could go ahead and remove feature flag.

The MR removes feature flag for conan package revisions support.

References

Extract Conan (C/C++ Package Manager) metadata ... (&14896 - closed)

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Related to &14896 (closed)