[ package:vm_service ] Update changelog for 7.2.0 release
[ package:vm_service ] Update changelog for 7.2.0 release

TEST=N/A
TBR=rmacnak@google.com

Change-Id: I1b4f4e937895f4772a01f7d4d75d89d1850cf6e5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/208301
Reviewed-by: Ben Konyi <67ffcaedcc3dc3d87dddb9627b72dd41756b31b1@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk