test: skip test-crypto-dh-keys on armv6 and armv7

The test is too slow to run on the Raspberry Pi bots. (It takes over 500
seconds to run on Pi 3 bots and over 900 seconds  on Pi 2 bots.) Skip
it on armv6 and armv7.

Refs: #34289

PR-URL: #38076
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/pummel/test-crypto-dh-keys.js

@@ -21,8 +21,14 @@
 
 'use strict';
 const common = require('../common');
-if (!common.hasCrypto)
+if (!common.hasCrypto) {
   common.skip('node compiled without OpenSSL.');
+}
+
+if ((process.config.variables.arm_version === '6') ||
+  (process.config.variables.arm_version === '7')) {
+  common.skip('Too slow for armv6 and armv7 bots');
+}
 
 const assert = require('assert');
 const crypto = require('crypto');