This PR was squashed before being merged into the 3.4 branch (closes #30227).

Discussion
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Update validators.bg.xlf

Translated 83, 84, & 85

| Q             | A
| ------------- | ---
| Branch?       | master for features / 3.4 up to 4.2 for bug fixes <!-- see below -->
| Bug fix?      | yes
| New feature?  | no <!-- don't forget to update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #30151
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

<!--
Write a short README entry for your feature/bugfix here (replace this comment block.)
This will help people understand your PR and can be used as a start of the Doc PR.
Additionally:
 - Bug fixes must be submitted against the lowest branch where they apply
   (lowest branches are regularly merged to upper ones so they get the fixes too).
 - Features and deprecations must be submitted against the master branch.
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Commits
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4f3bc6b Update validators.bg.xlf

This PR was merged into the 3.4 branch.

Discussion
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[Validator] Improve Bulgarian translations.

| Q             | A
| ------------- | ---
| Branch?       | 3.4 <!-- see below -->
| Bug fix?      | no
| New feature?  | no <!-- don't forget to update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | none   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | none <!-- required for new features -->

<!--
Write a short README entry for your feature/bugfix here (replace this comment block.)
This will help people understand your PR and can be used as a start of the Doc PR.
Additionally:
 - Bug fixes must be submitted against the lowest branch where they apply
   (lowest branches are regularly merged to upper ones so they get the fixes too).
 - Features and deprecations must be submitted against the master branch.
-->

This pull request is an improvement on top of #30227 and improves translations in the following ways:

- Make consistent how `This` word is translated.
- Make consistent how `This value` is translated.
- Fix capitalization rules for abbreviations.
- Change `email` to `имейл` (this is a word in the official Bulgarian dictionary).
- Removes unnecessary words in brackets.

Feel free to comment and criticize I'm not a professional translator.

Commits
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d15c76c Make translations consistent with other translations.