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.


server/src/test/java/org/elasticsearch/indices/recovery/RecoverySettingsTests.java
private Set<String> roles;
        private ByteSizeValue physicalMemory;
        private @Nullable ByteSizeValue networkBandwidth;
        private @Nullable ByteSizeValue diskReadBandwidth;
        private @Nullable ByteSizeValue diskWriteBandwidth;
        private @Nullable ByteSizeValue indicesRecoveryMaxBytesPerSec;
        private @Nullable Double operatorDefaultFactor;
        private @Nullable Double maxOvercommitFactor;
        NodeRecoverySettings withRole(String role) {
            this.roles = Set.of(Objects.requireNonNull(role));
            return this;
        }
        NodeRecoverySettings withRoles(Set<String> roles) {
            this.roles = Objects.requireNonNull(roles);
            return this;
        }
        NodeRecoverySettings withMemory(ByteSizeValue physicalMemory) {
            this.physicalMemory = Objects.requireNonNull(physicalMemory);
            return this;
        }
        NodeRecoverySettings withRandomMemory() {
            return withMemory(ByteSizeValue.ofBytes(randomLongBetween(ByteSizeUnit.GB.toBytes(1L), ByteSizeUnit.TB.toBytes(4L))));
        }
        NodeRecoverySettings withIndicesRecoveryMaxBytesPerSec(ByteSizeValue indicesRecoveryMaxBytesPerSec) {
            this.indicesRecoveryMaxBytesPerSec = Objects.requireNonNull(indicesRecoveryMaxBytesPerSec);
            return this;
        }
        NodeRecoverySettings withRandomIndicesRecoveryMaxBytesPerSec() {
            if (randomBoolean()) {
                withIndicesRecoveryMaxBytesPerSec(randomByteSizeValue());