Env Var Masking breaks when updating values in sync

[shivaygupta-dotcom]

We identified a couple of issues with environment variable masking in decK commands:

1. When an environment variable value is updated, the previous value is leaked in the output instead of being masked .
2. If a secret contains a value (for example, "x"), every occurrence of that value in the output gets masked, even when it is unrelated to the actual secret.