Validation check broken for 2 consecutive line breaks on translation pages

AFFECTS:

• xwiki:Main.SolrTranslations (en, sk, es, de, fr, pt_BR, ca, no, hr, nl, sv, lv)
• xwiki:Main.ActivityTranslations (en, zh_TW, vi, it, ru, cs, pt_BR, es, de, lv, fr, ro, tr, ca, zh, gl, hr, sv, sk, ko, da)
• xwiki:SkinsCode.Translations (en, fr, sk, hr, lv)
• xwiki:AppWithinMinutes.Translations (en, sv, pt_BR, it, ca, ru, da, nl, es, cs, fr, de, tr, sk, hr, lv)
• xwiki:CKEditor.Translations (en, fr, hr)
• etc.

ERROR:

• org.xwiki.test.webstandards.CustomDutchWebGuidelinesValidationTest.Validating HTML5 Dutch Web Guidelines validity for: xwiki:Main.SolrTranslations executed with credentials Admin:admin (from org.xwiki.test.webstandards.AllTests)
• ERROR: Consecutive <br> (line break) tags have been found. This usually occurs so as to create more white space. Use <p> tags and CSS to obtain the desired effect.

INVALIDATES:

• Dutch Guidelines: validateRpd3s4()
  • https://github.com/xwiki/xwiki-platform/blob/master/xwiki-platform-tools/xwiki-platform-tool-standards-validator/src/main/java/org/xwiki/validator/DutchWebGuidelinesValidator.java#L454
• R-pd.3.4 "Use the p (paragraph) element to indicate paragraphs. Do not use the br (linebreak) element to separate paragraphs."

EXPLANATION:

• I've run the HTML content through ckeditor-4/accessibility-checker/ and wave.webaim.org and I got no error for these consecutive <br> elements. Also checked the WCAG 2.1 (https://www.w3.org/TR/WCAG/) and didn't found anything specific about this.
• Our validator breaks since the translations pages are in syntax Plain 1.0 and we add spaces between translations to better group them.

FIXES:

• VAR1: Remove the validation check
• VAR2: Add an exception for the standard translation pages since the effect is WCAG valid and we don't plan to remove the line breaks. The problem with this approach (that we are currently applying for Syntax pages) is the scalability. We would need to update the exception list every time we would add a such translation pages.
• VAR3: Launch the error only if we encounter more than 2 consecutive breaks