**Elasticsearch version** (`bin/elasticsearch --version`): 7.16 (earlier too), 8.0, 8.1

**Description of the problem including expected versus actual behavior**:
Currently, the rollover requests are not cancellable, irrespective of the underlying incoming HTTP channel being closed (eg. by a proxy). This could result in clients receiving `504` and retrying the rollovers, resulting in multiple rollover operations being processed (some products issue rollovers without specifying conditions, so this could translate in multiple subsequent rollovers being executed).

This proposes using the `RestCancellableNodeClient` infrastructure for the rollover API, such that elasticsearch can react to the incoming HTTP connection being closed by cancelling the rollover operation.

server/src/main/java/org/elasticsearch/action/admin/indices/rollover/RolloverRequest.java
MaxDocsCondition maxDocsCondition = new MaxDocsCondition(numDocs);
        if (this.conditions.containsKey(maxDocsCondition.name)) {
            throw new IllegalArgumentException(maxDocsCondition.name + " condition is already set");
        }
        this.conditions.put(maxDocsCondition.name, maxDocsCondition);
    }
    /**
     * Adds a size-based condition to check if the index size is at least <code>size</code>.
     */
    public void addMaxIndexSizeCondition(ByteSizeValue size) {
        MaxSizeCondition maxSizeCondition = new MaxSizeCondition(size);
        if (this.conditions.containsKey(maxSizeCondition.name)) {
            throw new IllegalArgumentException(maxSizeCondition + " condition is already set");
        }
        this.conditions.put(maxSizeCondition.name, maxSizeCondition);
    }
    /**
     * Adds a size-based condition to check if the size of the largest primary shard is at least <code>size</code>.
     */
    public void addMaxPrimaryShardSizeCondition(ByteSizeValue size) {
        MaxPrimaryShardSizeCondition maxPrimaryShardSizeCondition = new MaxPrimaryShardSizeCondition(size);
        if (this.conditions.containsKey(maxPrimaryShardSizeCondition.name)) {
            throw new IllegalArgumentException(maxPrimaryShardSizeCondition + " condition is already set");
        }
        this.conditions.put(maxPrimaryShardSizeCondition.name, maxPrimaryShardSizeCondition);
    }
    /**
     * Adds a size-based condition to check if the docs of the largest primary shard has at least <code>numDocs</code>
     */
    public void addMaxPrimaryShardDocsCondition(long numDocs) {