[lldb] Remove pydoc import during script interpreter init

[kastiglione]

Summary

The Python script interpreter imports pydoc during initialization, but this can be
slow in some cases, and doesn't seem to be necessary any more.

This can be slow because pydoc may execute shell commands (for example xcrun on
macOS). The shell commands may have variable performance, depending on their caches and
search space.

The 2012 bug report for the original commit (f71a8399997bfdc1ddeeb30c6a8897554a11c382)
says the following:

"script help" in lldb pipes the help documentation through less(1) but there's some
problem with the key handling and often the keys you'd use to move in less (space to
move down a page, 'q' to quit) are not received by less (they're going to lldb
instead)

This was resolved at the time by overriding pydoc's pager to be the plainpager
function.

I have manually tested script help(lldb.SBDebugger) and found no issues with the
pager, including using "space" for paging, "/" for searching, and "q" for quitting.

The presumption is that lldb and/or Python have improved I/O handling that eliminates
the original problem.

The original bug report gave an ~/.lldbinit workaround:

script import pydoc; pydoc.pager = pydoc.plainpager

Note that calling Python's help() will import pydoc, but this will only happen for
users who use help() from the script command.

rdar://105015455

lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp

ScriptInterpreterPythonImpl::ScriptInterpreterPythonImpl(Debugger &debugger)
   PyRun_SimpleString(run_string.GetData());
 
   // WARNING: temporary code that loads Cocoa formatters - this should be done
   // on a per-platform basis rather than loading the whole set and letting the
   // individual formatter classes exploit APIs to check whether they can/cannot
   // do their task
   run_string.Clear();
   run_string.Printf(
-      "run_one_line (%s, 'import lldb.formatters, lldb.formatters.cpp, pydoc')",
+      "run_one_line (%s, 'import lldb.formatters, lldb.formatters.cpp')",
       m_dictionary_name.c_str());
   PyRun_SimpleString(run_string.GetData());
   run_string.Clear();
 
   run_string.Printf("run_one_line (%s, 'import lldb.embedded_interpreter; from "
                     "lldb.embedded_interpreter import run_python_interpreter; "
                     "from lldb.embedded_interpreter import run_one_line')",
                     m_dictionary_name.c_str());
   PyRun_SimpleString(run_string.GetData());
   run_string.Clear();
 
   run_string.Printf("run_one_line (%s, 'lldb.debugger_unique_id = %" PRIu64
-                    "; pydoc.pager = pydoc.plainpager')",
+                    "')",
                     m_dictionary_name.c_str(), m_debugger.GetID());
   PyRun_SimpleString(run_string.GetData());
 }
 
 ScriptInterpreterPythonImpl::~ScriptInterpreterPythonImpl() {
   // the session dictionary may hold objects with complex state which means
   // that they may need to be torn down with some level of smarts and that, in
   // turn, requires a valid thread state force Python to procure itself such a