Update default for BraveEnableAutoTranslate in the code

[atuchin-m]

The feature BraveEnableAutoTranslate should be disabled by default (the same as in Griffin).

Griffin issue: brave/brave-variations#480 (The steps to verify can be found here)

STR for QA:

Please take a look brave/brave-core#16483 (comment) for STR/Cases for Desktop & Android.

[kjozwiak]

The above requires 1.47.171 or higher for 1.47.x verification 👍

[GeetaSarvadnya]

Verification PASSED on

Brave | 1.47.171 Chromium: 109.0.5414.87 (Official Build) (64-bit)
-- | --
Revision | 2dc18eb511c56e012081b4abc9e38c81c885f7d4-refs/branch-heads/5414@{#1241}
OS | Windows 10 Version 21H2 (Build 19044.2486)

Prerequisite: ensure that you don't relaunch the browser and pull BraveAutoTranslateStudy:AutoTranslateDisabled when verifying the above. Basically need to makes sure that the browser isn't restarted after first launch so it doesn't pull and apply the seed file from Griffin. This way, you know you're QAing the change from b-c.

• ensured that Always translate [language] isn't visible under the hamburger menu via Brave Translate
• ensured that Always translate [language] never appears under the languages being detected after translating several sites
• ensured that Brave Translate appears within the omnibox when it detects a supported locale that it can translate
• ensured that you can translate several websites without any issues (mostly checked on Wikipedia and tried a few randoms)
• ensured that the auto translate feature is still disabled once you've restarted the browser and pulled BraveAutoTranslateStudy:AutoTranslateDisabled

Example	Example	Example	Example	Example

Traslated few languages successfully:

Example	Example	Example	Example

[Uni-verse]

Verified on Samsung Galaxy S21 5G using version:

Brave	1.47.171 Chromium: 109.0.5414.87 (Official Build) (64-bit) 
Revision	2dc18eb511c56e012081b4abc9e38c81c885f7d4-refs/branch-heads/5414@{#1241}
OS	Android 13; Build/TP1A.220624.014

Using STR/Test Plan in brave/brave-core#16483 (comment)

Prerequisite: ensure that you don't relaunch the browser and pull BraveAutoTranslateStudy:AutoTranslateDisabled when verifying the above. Basically need to makes sure that the browser isn't restarted after first launch so it doesn't pull and apply the seed file from Griffin. This way, you know you're QAing the change from b-c.

• ensured that Always translate [language] isn't visible under the hamburger menu via Brave Translate
• ensured that Brave Translate appears at the bottom of the viewport when it detects a supported locale that it can translate
• ensured that you can translate several websites without any issues (mostly checked on Wikipedia and tried a few randoms)
• ensured that the auto translate feature is still disabled once you've restarted the browser and pulled BraveAutoTranslateStudy:AutoTranslateDisabled
• ensured that Use Brave Translate is enabled by default via Settings -> Languages
• ensured that disabling Use Brave Translate via Settings -> Languages disables Brave Translate
• ensured that you're not seeing Brave Translate when visiting websites that can be translated
• ensured that re-enabling works as expected and re-enables the feature without any issues (checked that it's working as well)

Example	Example	Example	Example	Example	Example