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/main/java/org/elasticsearch/indices/recovery/RecoverySettings.java
* Disk's write bandwidth allocated for this node. This bandwidth is expressed for write operations that have the default block size of
     * {@link #DEFAULT_CHUNK_SIZE}.
     */
    public static final Setting<ByteSizeValue> NODE_BANDWIDTH_RECOVERY_DISK_WRITE_SETTING = bandwidthSetting(
        "node.bandwidth.recovery.disk.write"
    );
    /**
     * Disk's read bandwidth allocated for this node. This bandwidth is expressed for read operations that have the default block size of
     * {@link #DEFAULT_CHUNK_SIZE}.
     */
    public static final Setting<ByteSizeValue> NODE_BANDWIDTH_RECOVERY_DISK_READ_SETTING = bandwidthSetting(
        "node.bandwidth.recovery.disk.read"
    );
    /**
     * Network's read bandwidth allocated for this node.
     */
    public static final Setting<ByteSizeValue> NODE_BANDWIDTH_RECOVERY_NETWORK_SETTING = bandwidthSetting(
        "node.bandwidth.recovery.network"
    );
    static final double DEFAULT_FACTOR_VALUE = 0.4d;
    /**
     * Default factor as defined by the operator.
     */
    public static final Setting<Double> NODE_BANDWIDTH_RECOVERY_OPERATOR_FACTOR_SETTING = operatorFactorSetting(
        "node.bandwidth.recovery.operator.factor",
        DEFAULT_FACTOR_VALUE
    );
    public static final Setting<Double> NODE_BANDWIDTH_RECOVERY_OPERATOR_FACTOR_WRITE_SETTING = operatorFactorSetting(
        "node.bandwidth.recovery.operator.factor.write"
    );