Remove code to suggest installing Google Translate Extension

[atuchin-m]

After enabling the new Translate feature by default we can remove the code to install Goggle Translate extension (including the bubble).

The behaviour for the existing Google Translate extension users is discussed in #24715

[atuchin-m]

Test plan:

1. Sanity check that build-in translation works (any desktop platform + android);
2. Check that translation bubble and the icon in the omnibox is unchanged (any desktop platform);
3. Check that Enable internal translate engine (brave-translate-go) flag is removed from brave://flags (desktop + android)

[stephendonner]

Verified PASSED using

Brave	1.45.75 Chromium: 106.0.5249.65 (Official Build) beta (x86_64)
Revision	3269dc3633cdd2ab94546fdbe54962e45b17a6e0-refs/branch-heads/5249@{#580}
OS	macOS Version 11.7 (Build 20G817)

Case 1: in-build translation

example	example

Case 2: translation "bubble" and icon

Case 3: confirmed that the brave-translate-go flag is removed from brave://flags

Confirmed I was not prompted to install Google Translate, and Brave Translate worked without any additional setup

[MadhaviSeelam]

Verification PASSED using

Brave | 1.45.77 Chromium: 106.0.5249.65 (Official Build) beta (64-bit)
-- | --
Revision | 3269dc3633cdd2ab94546fdbe54962e45b17a6e0-refs/branch-heads/5249@{#580}
OS | Windows 11 Version 21H2 (Build 22000.978)

Case 1: Verified Built-in translation works as expected and additionally not prompted to install Google Translate extension

Ex1	Ex2

Case 2: Verified translation bubble and the icon in the omnibox displayed as expected

Case 3: Verified #brave-translate-go flag is removed from brave://flags

[btlechowski]

Verification passed on

Brave	1.45.90 Chromium: 106.0.5249.103 (Official Build) beta (64-bit)
Revision	182570408a1f25ab2731ef5f283b918df9b9f956-refs/branch-heads/5249_91@{#6}
OS	Ubuntu 18.04 LTS

Case 1: in-build translation

Case 2: translation "bubble" and icon

Case 3: confirmed that the brave-translate-go flag is removed from brave://flags

Confirmed I was not prompted to install Google Translate, and Brave Translate worked without any additional setup

[GeetaSarvadnya]

Verification PASSED on vivo x70 Pro version 12 running Bravemonoarm64.apk_1.45.108

Case 1: in-build translation

Case 2: translation "bubble" and icon

Example	Example

Case 3: confirmed that the brave-translate-go flag is removed from brave://flags

Example	Example

Confirmed I was not prompted to install Google Translate, and Brave Translate worked without any additional setup

---

Verification PASSED on Samsung Galaxy Tab A7 version 12 running Bravemonoarm64.apk_1.45.108

Case 1: in-build translation

Case 2: translation "bubble" and icon

Example	Example

Case 3: confirmed that the brave-translate-go flag is removed from brave://flags

Confirmed I was not prompted to install Google Translate, and Brave Translate worked without any additional setup