We limit the number of concurrent blob downloads per node and per recovery, but if a user configures too many concurrent recoveries they may run out of per-node download permits which yields the following message:

> Unable to acquire permit to use snapshot files during recovery, this recovery will recover index files from the source node. Ensure snapshot files can be used during recovery by setting [indices.recovery.max_concurrent_snapshot_file_downloads] to be no greater than [25]

The `[25]` here is wrong, the 25 permits are shared across all inbound recoveries so we should divide the suggested value by `cluster.routing.allocation.node_concurrent_incoming_recoveries`. In extreme cases the user may have configured so many concurrent recoveries that the only reasonable limit is zero, and in that case we should suggest setting `indices.recovery.use_snapshots: false` instead.


test/framework/src/main/java/org/elasticsearch/test/MockLogAppender.java
this.saw = false;
        }
        @Override
        public void match(LogEvent event) {
            if (event.getLevel().equals(level) && event.getLoggerName().equals(logger) && innerMatch(event)) {
                if (Regex.isSimpleMatchPattern(message)) {
                    if (Regex.simpleMatch(message, event.getMessage().getFormattedMessage())) {
                        saw = true;
                    }
                } else {
                    if (event.getMessage().getFormattedMessage().contains(message)) {
                        saw = true;
                    }
                }
            }
        }
        public boolean innerMatch(final LogEvent event) {
            return true;
        }
    }
    public static class UnseenEventExpectation extends AbstractEventExpectation {
        public UnseenEventExpectation(String name, String logger, Level level, String message) {
            super(name, logger, level, message);
        }
        @Override
        public void assertMatched() {
            assertThat("expected not to see " + name + " but did", saw, equalTo(false));
        }
    }
    public static class SeenEventExpectation extends AbstractEventExpectation {