fix: search preferred provider and wekeo job error handling

[jlahovnik]

Contains the following changes:

• The preferred provider is not changed anymore when a search or download is executed. If a provider is given in the request, it will be used (if it offers the selected product type) but the preferred provider is not changed. If no provider is given, the configured preferred provider is used.

Fixes #783

• an error is raised when the creation of a data request job fails for wekeo

[github-actions]

Test Results

       4 files  ±0         4 suites  ±0   6m 6s ⏱️ +26s
   404 tests +1     402 ✔️ +1    2 💤 ±0  0 ❌ ±0 
1 616 runs  +4  1 556 ✔️ +4  60 💤 ±0  0 ❌ ±0 

Results for commit 1a81749. ± Comparison against base commit 9acf017.

♻️ This comment has been updated with latest results.

[github-actions]

Code Coverage (Ubuntu)

File	Coverage
All files	82%	✅

Minimum allowed coverage is 70%

Generated by 🐒 cobertura-action against 1a81749

[github-actions]

Code Coverage (Windows)

File	Coverage
All files	76%	✅

Minimum allowed coverage is 70%

Generated by 🐒 cobertura-action against 1a81749

[sbrunato]

Please also add a test to check the new behavior with preferred providers