ccmlib/node.py: extract logic of running nodetool into separate method

Separate parameterizing nodetool and actually invoking it. The
parameterizing is about to diverege for node.py and scylla_node.py, so
this separation allows us to reuse just the invoke logic, while letting
the two go on its separate ways when it comes to parameterizing.

ccmlib/node.py

@@ -808,6 +808,26 @@ def wait_for_compactions(self,
             time.sleep(1)
         raise TimeoutError(f"Waiting for compactions timed out after {idle_timeout} seconds with pending tasks remaining: {output}.")
 
+    def _do_run_nodetool(self, nodetool, capture_output=True, wait=True, timeout=None, verbose=True):
+        if capture_output and not wait:
+            raise common.ArgumentError("Cannot set capture_output while wait is False.")
+        env = self.get_env()
+        if verbose:
+            self.debug(f"nodetool cmd={nodetool} wait={wait} timeout={timeout}")
+        if capture_output:
+            p = subprocess.Popen(nodetool, universal_newlines=True, env=env, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+            stdout, stderr = p.communicate(timeout=timeout)
+        else:
+            p = subprocess.Popen(nodetool, env=env, universal_newlines=True)
+            stdout, stderr = None, None
+
+        if wait:
+            exit_status = p.wait(timeout=timeout)
+            if exit_status != 0:
+                raise NodetoolError(" ".join(nodetool), exit_status, stdout, stderr)
+
+        return stdout, stderr
+
     def nodetool(self, cmd, capture_output=True, wait=True, timeout=None, verbose=True):
         """
         Setting wait=False makes it impossible to detect errors,
@@ -816,9 +836,6 @@ def nodetool(self, cmd, capture_output=True, wait=True, timeout=None, verbose=Tr
         When wait=True, timeout may be set to a number, in seconds,
         to limit how long the function will wait for nodetool to complete.
         """
-        if capture_output and not wait:
-            raise common.ArgumentError("Cannot set capture_output while wait is False.")
-        env = self.get_env()
         if self.is_scylla() and not self.is_docker():
             host = self.address()
         else:
@@ -830,21 +847,8 @@ def nodetool(self, cmd, capture_output=True, wait=True, timeout=None, verbose=Tr
         # see https://www.oracle.com/java/technologies/javase/8u331-relnotes.html#JDK-8278972
         nodetool.extend(['-h', host, '-p', str(self.jmx_port), '-Dcom.sun.jndi.rmiURLParsing=legacy'])
         nodetool.extend(cmd.split())
-        if verbose:
-            self.debug(f"nodetool cmd={cmd} wait={wait} timeout={timeout}")
-        if capture_output:
-            p = subprocess.Popen(nodetool, universal_newlines=True, env=env, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-            stdout, stderr = p.communicate(timeout=timeout)
-        else:
-            p = subprocess.Popen(nodetool, env=env, universal_newlines=True)
-            stdout, stderr = None, None
-
-        if wait:
-            exit_status = p.wait(timeout=timeout)
-            if exit_status != 0:
-                raise NodetoolError(" ".join(nodetool), exit_status, stdout, stderr)
 
-        return stdout, stderr
+        return self._do_run_nodetool(nodetool, capture_output, wait, timeout, verbose)
 
     def dsetool(self, cmd):
         raise common.ArgumentError('Cassandra nodes do not support dsetool')