BE: Impl a default timeout for http requests

[o-afanasenko]

What changes did you make? (Give an overview)
Added default timeout to HttpClient because without it some requests can never end, especially for high-load kafka connect.

For us this fixed problem when Kafka connectors page was infinitely in a loading state. Root cause is a kafka connect instance with Debezium connectors which sometimes doesn't respond. But this shouldn't block viewing of other connectors.

How Has This Been Tested? (put an "x" (case-sensitive!) next to an item)

• No need to
• Manually (see comment above)
• Unit checks
• Integration checks
• Covered by existing automation

Checklist (put an "x" (case-sensitive!) next to all the items, otherwise the build will fail)

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (e.g. ENVIRONMENT VARIABLES)
• My changes generate no new warnings (e.g. Sonar is happy)
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged

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