Deactivate Vault Config Source refresh if running in non blocking thread

[vsevel]

Fixes #15821
I am not sure we can do better at this point. This means this is a slight regression compared to the previous implementation with with okhttp, where we would block on the vault call in the vertx thread (which is not good), but at least functionally, we would be able to refresh the cache.
With the current implementation, we have to know that the vault config source cache refresh will only happen in non vertx threads. another approach would be to do the refresh from a timer, rather than doing it from the app thread. but this would require a dedicated thread. Ideally, it would be better to be able to register a callback on a central timer service.
In the meantime this fix will avoid the issue found in #15821

[sberyozkin]

@vsevel Hi Vincent, I'm pretty sure you can run it using the blocking executor but some more Uni changes may have to be applied, CC @cescoffier

[cescoffier]

@sberyozkin The issue here is that the method is synchronous (does not return a Uni). OF course, if it would return a Uni (as you did in the OIDC), then we would be able to use the same approach.

[sberyozkin]

Hi @cescoffier, @vsevel sorry missed it.

Interesting problem, how to get ConfigSource run in the async mode - @vsevel, would you like to open an issue and CC to @radcortez ? May be Quarkus can have ConfigSource extension which uses Uni etc...

[sberyozkin]

Forgot to add the approval but Clement's approval was enough for sure

[vsevel]

Interesting problem, how to get ConfigSource run in the async mode - @vsevel, would you like to open an issue and CC to @radcortez ? May be Quarkus can have ConfigSource extension which uses Uni etc...

here it is @sberyozkin #16058