Search string is replaced for duckduckgo upon upgrade in German locale

[btlechowski]

Follow up to #6187

The expected behavior is based on https://github.com/brave/internal/issues/647

Steps to Reproduce

1. Set system locale to German/Germany
2. Install 0.69.x https://github.com/brave/brave-browser/releases/tag/v0.69.123
3. Check duckduckgo search string in chrome://settings/searchEngines
4. Upgrade to 0.70.x
5. Check duckduckgo search string in chrome://settings/searchEngines

Actual result:

Search string is replaced after upgrade
Search string: https://duckduckgo.com/?q=%s&t=bravened

Expected result:

Search string is not replaced after upgrade
Search string: https://duckduckgo.com/?q=%s&t=brave

Reproduces how often:

Always

Brave version (brave://version info)

Brave	0.70.112 Chromium: 77.0.3865.90 (Official Build) beta (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	Windows 10 OS Version 1903 (Build 18362.175)

Brave	0.70.112 Chromium: 77.0.3865.90 (Official Build) beta (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	Ubuntu 18.04 LTS

cc @brave/legacy_qa @rebron @bsclifton

[GeetaSarvadnya]

The issue is reproducible when upgrade build (DE/Germany) from released version 0.69.139 to 0.70.113 and upgrade from 0.69.123 to 0.70.113

[LaurenWags]

Reproduced on macOS when upgrading from 0.69.135 to 0.70.115.

Prior to upgrade - using 0.69.135:

After upgrade - using 0.70.115:

Brave	0.70.115 Chromium: 77.0.3865.90 (Offizieller Build) beta (64-Bit)
Überarbeitung	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
Betriebssystem	macOS Version 10.13.6 (Build 17G5019)

[bsclifton]

Closing in favor of #6469