lib: source build replace the matching release

Instead of having an explicit vX.Y-dev version to be referenced
explicitly, a binary built from source replaces the matching
version. For instance, if forgejo/build-from-sources contains v9.0,

* the development branch is compiled from source
* the v9.0 artifact is uploaded
* prior to running any test, the artificat is downloaded and used
* the v9.0 binary is not downloaded from
  forgejo/experimental/integration because it is already present

The vX.Y release is built daily and the end-to-end tests run on it. If
a regression is introduced, it will be spotted within 24h.

Compiling from source is used when the Forgejo runs the end-to-end
suite on a specific pull request.

lib/lib.sh

@@ -70,18 +70,6 @@ function dependencies() {
     fi
 }
 
-function build_all() {
-    for dev in $RELEASE_NUMBERS; do
-        local forgejo=$DIR_BINARIES/forgejo-$dev-dev
-        if test -f $forgejo; then
-            log_info $dev already exists
-        else
-            $LIB_DIR/build.sh $dev $DIR_BINARIES
-            log_info $dev built from sources
-        fi
-    done
-}
-
 function retry() {
     rm -f $DIR/wait-for.out
     success=false