Standardize feature flag names

[efenderbosch]

It is easy to understand what the aws-cdk:enableDiffNoFail feature flag does.

However, feature flag names like aws-cdk/secretsmanager:parseOwnedSecretName are unclear. I don't know by reading the flag name if if enabling the flag will include or exclude the suffix. A better name for this flag might be aws-cdk/secretsmanager:excludeSecretNameSuffix.

[indrora]

I've opened an issue for this, #27058