[sonic-cfggen] remove lazy_re workaround due to many optimizations done

[stepanblyschak]

lazy_re had an issue when importing sonic-cfggen in another application that
uses re.search():

Traceback (most recent call last):
  File "/usr/local/bin/spm", line 8, in <module>
    sys.exit(cli())
  File "/usr/local/lib/python3.7/dist-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.7/dist-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.7/dist-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.7/dist-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/click/decorators.py", line 17, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/sonic_package_manager/main.py", line 202, in list
    click.echo(tabulate.tabulate(table_body, table_header))
  File "/usr/local/lib/python3.7/dist-packages/tabulate.py", line 1259, in tabulate
    has_invisible = re.search(_invisible_codes, plain_text)
  File "/usr/lib/python3.7/re.py", line 183, in search
    return _compile(pattern, flags).search(string)
  File "/usr/lib/python3.7/re.py", line 285, in _compile
    raise TypeError("first argument must be string or compiled pattern")
TypeError: first argument must be string or compiled pattern

There is no much imporvement of lazy_re today after many other good optimization work
done for sonic-cfggen. It served as a quick temporary solution.

Some quick test for fast-reboot and warm-reboot done on top of 201911 branch:

Fast-reboot: from ASIC reset to ports in up state:
with lazy_re: 18 sec
without lazy_re: 18 sec

Warm-reboot: LAG restoration time:
with lazy_re: 73 sec
without lazy_re: 72 sec

So, there is no real optimization since the number of sonic-cfggen is grately reduced
in latest SONiC. This means it is time to revert this change.

Signed-off-by: Stepan Blyschak [email protected]

Why I did it

Remove W/A that I introduced a while ago that seems no longer needed nor gives some improvement.

How I did it

Removed lazy_re.

How to verify it

Ran fast-reboot, warm-reboot and do not observe degradations.

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106

Description for the changelog

A picture of a cute animal (not mandatory but encouraged)