Switch to using wildcard to match expected error in E2E script

[jgwest]

What does this PR do / why we need it:

• I previously noticed that an expected error was not being filtered by our 'unexpected errors check'

2025-06-11T23:40:12Z ERROR Reconciler error '{"controller":' '"rolloutmanager",' '"controllerGroup":' '"argoproj.io",' '"controllerKind":' '"RolloutManager",' '"RolloutManager":' '{"name":"test-rollouts-manager-2","namespace":"argo-rollouts"},' '"namespace":' '"argo-rollouts",' '"name":' '"test-rollouts-manager-2",' '"reconcileID":' '"2794f12c-8cef-4892-ba2a-6e154a8fdb32",' '"error":' '"clusterrolebindings.rbac.authorization.k8s.io' '\"argo-rollouts\"' already 'exists"}'

• Grepping out this error is difficult due to use of ' " \ characters, so I've just switched to using simple regexp to ignore that punctuation.

[jparsai]

LGTM @jgwest

[jgwest]

Thanks @jparsai!