* fix inconsistent behaviors with prometheus when scraping
1. address https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4959. skip job with wrong syntax in `scrape_configs` with error logs instead of exiting;
2. show error messages on vmagent /targets ui if there are wrong auth configs in `scrape_configs`, previously will print error logs and do scrape without auth header;
3. don't send requests if there are wrong auth configs in:
1. vmagent remoteWrite;
2. vmalert datasource/remoteRead/remoteWrite/notifier.
* add changelogs
* address review comments
* fix ut
d7dd7614eb