adapter: Change default query caching mode to async

We've decided to change the default query caching mode to async from
inrequestpath, since if the query takes a long time to be created (eg
because we have to create a large index in a base table), inrequestpath
could block queries for arbitrarily long amounts of time, and it's
likely a better user experience to just let the query run upstream while
that's happening (which is what async does).

Fixes: ENG-2121
Change-Id: I25c93bdd6e8efc56cfa1b6d90589a5643d094224
Reviewed-on: https://gerrit.readyset.name/c/readyset/+/3799
Tested-by: Buildkite CI
Reviewed-by: Dan Wilbanks <dan@readyset.io>

readyset-client-adapter/src/lib.rs

@@ -193,7 +193,7 @@ pub struct Options {
     #[clap(
         long,
         env = "QUERY_CACHING",
-        default_value = "inrequestpath",
+        default_value = "async",
         possible_values = &["inrequestpath", "explicit", "async"]
     )]
     query_caching: MigrationStyle,