Upgrade webpack 5.91.0 → 5.96.1 (#202534)

## Summary

Upgrades references to webpack5 from v5.91.0 to v5.96.1

A v4 to v5 upgrade is being explored here:
#191106

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Co-authored-by: kibanamachine <[email protected]>
(cherry picked from commit f8860e9)

# Conflicts:
#	yarn.lock