connpool: do not wait in call() if all checked

This patch changes `connpool.call()` method. Previously, if there were
instances satisfying the static requirements but not the dynamic ones
the method waited until the timeout checking if they start to satisfy
the requirements.

It seems impractical. Existing dynamic options is unlikely to change
during this small period of time. Let's not wait these instances and
exit instead if no suitable instances have been found.

Assume a cluster with two instances `i-001` and `i-002`. `i-001` is
alive and RW. `i-002` is dead.

Previous version of `connpool.call(<func>, <args>, {mode = 'ro'})` would
wait in that case since it expected for an RO instance to appear.

New version of `connpool.call(<func>, <args>, {mode = 'ro'})` just
ends up with a "no candidates found" error.

Part of tarantool#10330

NO_DOC=small change of an undocumented behavior, related will be added
       later
NO_CHANGELOG=will be added later
NO_TEST=related logic will be tested later in the patchset

Author: georgiy-belyanin

src/box/lua/connpool.lua

@@ -241,10 +241,12 @@ end
 --- This method connects to the specified instances and returns
 --- the set of successfully connected ones.
 ---
---- Specifying a callback accepting an instance name and returning
---- a boolean value in `opts.any` changes the behavior to connect
---- to multiple instances until there is at least one satisfying
---- the condition or the timeout occurs.
+--- If a callback accepting an instance name and returning a
+--- boolean value is provided in `opts.any` the method connects
+--- to multiple instances and try to find one satisfying the
+--- callback. It lasts until all of the instances are known to
+--- be unsuitable (either failed or not satisfying the callback)
+--- or the timeout is reached.
 function pool_methods.connect_to_multiple(self, instances, opts)
     checks('table', 'table', {
         any = '?function',
@@ -291,10 +293,10 @@ function pool_methods.connect_to_multiple(self, instances, opts)
             if fun.iter(instances):any(opts.any) then
                 break
             end
-        else
-            if fun.iter(instances):all(is_instance_checked) then
-                break
-            end
+        end
+
+        if fun.iter(instances):all(is_instance_checked) then
+            break
         end
 
         self._connection_mode_update_cond:wait(delay)