fix: add secret survey variable on opentofu task issue #2322

[bdoubrovine]

This pull request introduces enhancements to the getEnvironmentExtraVars method in services/tasks/LocalJob.go to improve the handling of secret variables. The most important change involves merging secret variables into the existing environment variables while ensuring the secret is reset after processing.

Enhancements to secret variable handling:

• Added a new map, extraSecretVars, to handle secret variables separately and parse them from the t.Secret JSON string. If parsing fails, the method returns an error.
• Reset the t.Secret field to an empty JSON object ("{}") after processing to ensure that secrets are not retained in memory.
• Merged the parsed extraSecretVars into the extraVars map using maps.Copy, consolidating all variables into a single map for further use.

#2322 and #2287