Closes #31673

This change makes test-stem faster and more reliable.

Use "make test-stem-full" to run all of stem's tests.

Closes ticket 31554.

Sebastian Hahn authored Aug 20, 2019 and teor committed Aug 22, 2019

The main build doesn't use HARDENING_OPTIONS, so the exclude shouldn't,
either. Reduces the number of builders by one.

New IP address from 194.109.206.212 to 45.66.33.45.

Signed request from Alex de Joode, operator of dizum:
https://trac.torproject.org/projects/tor/ticket/31406

Published descriptor by dizum on August 12th, 2019:

--
r dizum fqbq1v2DCDxTj0QDi7+gd1h911U GZmZtCLaPDQNxkhIFj8UcgTRAuA 2019-08-12 15:28:40 45.66.33.45 443 80
s Authority Fast Running Stable V2Dir Valid
v Tor 0.4.0.5
pr Cons=1-2 Desc=1-2 DirCache=1-2 HSDir=1-2 HSIntro=3-4 HSRend=1-2 Link=1-5 LinkAuth=1,3 Microdesc=1-2 Relay=1-2 Padding=1
w Bandwidth=20 Unmeasured=1
p reject 1-65535
--

Finally, confirmed by DNS:

  $ dig +short tor.dizum.com
  45.66.33.45

Closes #31406

Signed-off-by: David Goulet <dgoulet@torproject.org>

Delete src/or/buffers.c which was fixup'ed in 0.2.9 but moved in 0.3.5.
The 0.2.9 fix is not required for the 0.3.5 patch.
Resolves merge conflict caused by 30041.