KeycloakAuthzClient should have a reasonable default upper limit wait time for exponential backoff

[xuz10]

In KeycloakAuthzClient, the default try policy for http error is max 20 times, for 1st attempt wait 100ms, for following attempts double wait time of previous one.
With this setting at 20th attempt client will wait 2^19 *100 ms = 14.56h before retrying.

We've got a system once had a DNS issue to keycloak server. When the DNS issue was resolved, the client was stuck at19th retry. And client could not recover without waiting another 7 hours.

It is true that KeycloakAuthzClientBuild has offered method to override default http retry configs, but the option is not viable to be configured via EventStreamClientFactory via PravegaKeycloakCredentials.

There should be a reasonable default upper limit wait time set in KeycloakAuthzClient itself to limit it to minutes maximum.

[xinglan500]

Looking forward a fast improvement.