Standardize boolean values and update .env file pattern

[hcaumo]

Replace YES/NO with true/false for boolean variables in .env file. Ensure consistency across the codebase by removing the need for parseBooleanFromText.
Relates to:

#1391 - Standardize boolean values and fix pattern for .env file

Background
What does this PR do?

This PR replaces the "YES" and "NO" values used in the .env file for boolean variables with true and false to ensure consistency across the codebase. It removes the need for the parseBooleanFromText function, simplifying the parsing logic.
What kind of change is this?

Testing
Where should a reviewer start?

The reviewer should begin by checking the .env file to ensure that all boolean variables are now using true or false instead of "YES" or "NO".
Detailed testing steps

Check the .env file and verify that all boolean variables (e.g., POST_IMMEDIATELY, TWITTER_SEARCH_ENABLE) now use true or false.
Ensure that no usage of parseBooleanFromText exists in the codebase anymore.
Test the functionality where these variables are used to ensure they work correctly as booleans.

The base branch was changed.

[odilitime]

what about if they use TRUE or yes or YES? parseBooleanFromText looks for yes/no.

falsish needs to be move into core/packages/parsers.ts

eliza/agent/src/index.ts

Line 435 in 4c658d7

function isFalsish(input: any): boolean {

And that's probably what we should be using