Remove Alpine Linux bootstrap daemon dockerfile.

[iphydf]

We can add it back when there is a test for it. For now, we don't know
whether it works and don't have tests to make sure it keeps working.

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This change is 

[iphydf]

@romik-g FYI.

[nurupo]

Reviewed 1 of 1 files at r1.
Reviewable status: 0 of 1 approvals obtained

[codecov]

Codecov Report

Merging #1210 into master will decrease coverage by 0.2%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master   #1210     +/-   ##
========================================
- Coverage    82.8%   82.6%   -0.3%     
========================================
  Files          82      80      -2     
  Lines       14647   14620     -27     
========================================
- Hits        12140   12087     -53     
- Misses       2507    2533     +26

Impacted Files	Coverage Δ
toxcore/net_crypto.c	92.8% <0%> (-1.9%)	⬇️
toxcore/LAN_discovery.c	83.9% <0%> (-1.9%)	⬇️
toxav/msi.c	63.6% <0%> (-0.9%)	⬇️
toxcore/TCP_connection.c	78% <0%> (-0.2%)	⬇️
toxcore/onion_client.c	95.3% <0%> (-0.2%)	⬇️
toxav/toxav.c	67.6% <0%> (ø)	⬆️
auto_tests/bootstrap_test.c
auto_tests/tcp_relay_test.c
toxcore/friend_connection.c	94.8% <0%> (+0.2%)	⬆️

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