Fix example recipes

[valeriupredoi]

Description

I am fixing the example recipes here: most of them just need titles, but the preprocessor_test one needed a bit more work done, I did the following to it:

• I removed the use of OBS data: one should be able to run this irrespective of OBS data availability; this fixes Issue in multimodel cube merge surfaced by running recipe_preprocessor_test.yml ESMValCore#1339 - note that all other functionality is preserved
• I added a title (d'oh!) - I excluded the myPersonal_diagnostic recipe since I set a title for that one in Add titles to recipes authored by predoi_valeriu #2333 (avoiding git conflicts)

• Closes Issue in multimodel cube merge surfaced by running recipe_preprocessor_test.yml ESMValCore#1339

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[valeriupredoi]

that was the fastest approval in the history of PR's @zklaus 😆 I need to add moar titles to the remainder of the examples recipes, and then will fix the the boxes then merge, but I needs lunch now 🍔

[zklaus]

Lunch? You mean dinner. 🇸🇪 Anyway, if it's not ready yet, best to keep it a draft PR.

[valeriupredoi]

yeps, cheers! will de-Draftify after lunch, ahem, dinner 🇸🇪

[mkitti]

While I appreciate the work of Julia Roberts, perhaps Julia Child may be more appropriate for testing recipes. On second thought you probably just mean Julia, the language.

[valeriupredoi]

cheers, I'll exclude Julia Roberts from the cast 😆