component/golang: Drop unused EOL versions (1.13, 1.16, 1.18, 1.20)

This reduces maintenance work. go1.4 and go1.17 are used for
bootstrapping. go1.15 is used for gitlab.

/reviewed-by @jerome @kirr @tomo
/reviewed-on nexedi/slapos!1713

component/golang/buildout.cfg

@@ -81,21 +81,6 @@ patches =
 [golang14:platform.machine() == 'aarch64']
 setarch = setarch arm
 
-[golang1.13]
-<= golang-common-pre-1.19
-url = https://go.dev/dl/go1.13.15.src.tar.gz
-md5sum = 4f4af14d88352a62761a9dcedf863ac0
-
-# go1.13 needs go1.4 to bootstrap
-environment-extra =
-  GOROOT_BOOTSTRAP=${golang14:location}
-
-patches +=
-  https://lab.nexedi.com/kirr/go/commit/a724597faa7506c74f56208bed5432abc0935264.patch#2465a69e70bef37f34a5b2b7c93ebbb7
-  https://lab.nexedi.com/kirr/go/commit/d5cb71524482154b23c9e582ff0be0fc6d2856b2.patch#cc8c7524d12ebd2fc9334063901a9054
-  https://lab.nexedi.com/kirr/go/commit/6dfc2256e2cd1ad46f3a5e9da85af6a70be7fba3.patch#fa9de83838b198490abec0a6a924ad8d
-  https://lab.nexedi.com/kirr/go/commit/28fbdd01d6c89db1e81e12bd05910fdec4c3b9b3.patch#c75e2eb7aaaeffdd3c507ec1beacd3ca
-
 [golang1.15]
 <= golang-common-pre-1.19
 url = https://go.dev/dl/go1.15.15.src.tar.gz
@@ -105,15 +90,6 @@ md5sum = 05fedd8289291eb2d91cd0c092b41aaa
 environment-extra =
   GOROOT_BOOTSTRAP=${golang14:location}
 
-[golang1.16]
-<= golang-common-pre-1.19
-url = https://golang.org/dl/go1.16.15.src.tar.gz
-md5sum = fda3664a020a79fabe2d0d5d9d10861f
-
-# go1.16 needs go1.4 to bootstrap
-environment-extra =
-  GOROOT_BOOTSTRAP=${golang14:location}
-
 [golang1.17]
 <= golang-common-pre-1.19
 url = https://golang.org/dl/go1.17.13.src.tar.gz
@@ -123,26 +99,6 @@ md5sum = 4476707f05cf6915ec1173038dc357a9
 environment-extra =
   GOROOT_BOOTSTRAP=${golang14:location}
 
-[golang1.18]
-<= golang-common-pre-1.19
-url = https://golang.org/dl/go1.18.10.src.tar.gz
-md5sum = 002b4daec72ab396dc023a5ec445a68a
-
-# go1.18 needs go1.4 or go1.17 to bootstrap.
-# We use go1.4 to reduce the amount of components which
-# need to be installed. See following note for rationale:
-# https://lab.nexedi.com/nexedi/slapos/merge_requests/1305#note_174936
-environment-extra =
-  GOROOT_BOOTSTRAP=${golang14:location}
-
-[golang1.20]
-<= golang-common-pre-1.21
-url = https://go.dev/dl/go1.20.14.src.tar.gz
-md5sum = 71103194b2ca39cc9cb943df9aa6154c
-# go1.20 requires go1.17.13 to bootstrap (see https://go.dev/doc/go1.20#bootstrap)
-environment-extra =
-  GOROOT_BOOTSTRAP=${golang1.17:location}
-
 [golang1.21]
 <= golang-common
 url = https://go.dev/dl/go1.21.13.src.tar.gz