fix(translations): improve Spanish translations (#12555)

There are still things to improve.

- We're inconsistent with our use of capital letters. There are still
sentences where every word starts with a capital letter, and it looks
ugly (this also happens in English, but to a lesser extent).
- We're inconsistent with the use of punctuation at the end.
- Sentences with variables like {{count}} can result in inconsistencies
if it's 1 and the noun is plural.
- The same thing happens in Spanish, but also with gender. It's
impossible to know without the context in which it's used.

---------

Co-authored-by: Paul Popus <paul@payloadcms.com>

test/admin/e2e/general/e2e.spec.ts

@@ -677,7 +677,7 @@ describe('General', () => {
 
       await expect(page.locator('.step-nav a').first().locator('span')).toHaveAttribute(
         'title',
-        'Tablero',
+        'Panel de Control',
       )
 
       await field.click()

test/i18n/e2e.spec.ts

@@ -98,7 +98,7 @@ describe('i18n', () => {
     await page.goto(serverURL + '/admin/account')
     await page.locator('div.rs__control').click()
     await page.locator('div.rs__option').filter({ hasText: 'Español' }).click()
-    await expect(page.locator('div.payload-settings h3')).toHaveText('Configuración de la carga')
+    await expect(page.locator('div.payload-settings h3')).toHaveText('Configuración de Payload')
 
     await page.goto(serverURL + '/admin/collections/collection1/create')
     await expect(page.locator('label[for="field-fieldDefaultI18nValid"]')).toHaveText(