[MD] Meta issues from UX sign-off meeting

[yibow98]

Experimental callout

• [MD] Datasource experimental callout wording #2614

Datasource listing page

• [MD] Datasource table column header wording #2615
• [MD] Datasource listing page delete button refactor #2616
• [MD] Datasource listing page create button in empty state #2617
• [MD] Datasource list page fail toast #2626

Datasource create page

• [MD] Datasource create page spacing between header description and Connection Details #2618
• [MD] Datasource create page endpoint field placeholder wording #2619
• [MD] Datasource create page toast that fail to save #2620

Datasource update page

• [MD] Datasource update page endpoint field refactor #2621
• [MD] Datasource update page bottom bar refactor #2622

[KrooshalUX]

Commented on issue #2616 for clarity, all others look accurate. Thanks @yibow98 !