Merge bitcoin/bitcoin#27674: ci: Fix "Number of CPUs" output

5d49d98 ci: Fix "Number of CPUs" output (Hennadii Stepanov)

Pull request description:

  This PR is a follow-up to bitcoin/bitcoin#27616:

  - on [master](https://api.cirrus-ci.com/v1/task/5809898840129536/logs/ci.log):
  ```
  Number of CPUs \(nproc\): $(nproc)
  ```

  - this [PR](https://api.cirrus-ci.com/v1/task/6495994095861760/logs/ci.log):
  ```
  Number of CPUs (nproc): 32
  ```

ACKs for top commit:
  MarcoFalke:
    lgtm ACK 5d49d98

Tree-SHA512: d97ee3587dbadb604a381aa9990b58d75441307fc98e7ae674436f8318200c8faef7171348655cdcc3ed360c8ca22eacf063cb430b826a40cb0952a436c511f3

Author: fanquake

ci/test/06_script_b.sh

@@ -13,7 +13,7 @@ if [ "$CI_OS_NAME" == "macos" ]; then
   echo "Number of CPUs: $(sysctl -n hw.logicalcpu)"
 else
   free -m -h
-  echo "Number of CPUs \(nproc\):" \$\(nproc\)
+  echo "Number of CPUs (nproc): $(nproc)"
   lscpu | grep Endian
 fi
 echo "Free disk space:"