[release/v1.2] cherry pick bug fixes and IPv6 to v1.2.2

[zhaohuabing]

• fix: tcp listener is rejected when no route attached (envoyproxy#4681)
• fix: remove backendrefs validation (#4705)
• fix: translator reports errors for existing clusters and secretes (#4707)
• xds: always use :: and IPv4Compact for dynamic listener (#4743)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 79.24528% with 11 lines in your changes missing coverage. Please review.

Project coverage is 65.54%. Comparing base (8a03f39) to head (222a0f2).

Files with missing lines	Patch %	Lines
internal/gatewayapi/securitypolicy.go	78.04%	6 Missing and 3 partials :warning:
internal/cmd/envoy/shutdown_manager.go	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release/v1.2 #4765 +/- ## ================================================ - Coverage 65.55% 65.54% -0.01% ================================================ Files 211 211 Lines 31943 31941 -2 ================================================ - Hits 20939 20937 -2 Misses 9760 9760 Partials 1244 1244 ```

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