Upgrade to Istio 1.7.7

Istio 1.7.7 has fixes for

https://repo1.dso.mil/platform-one/big-bang/bigbang/-/issues/65

Need additional images harded to match versions across components:

dsop/opensource/istio-1.7/pilot-1.7#5 (closed) dsop/opensource/istio-1.7/proxyv2-1.7#6 (closed)