Remove interactive build for telega-server, as it fails on Guix.
Modify the `telega-server--find-bin' function to only use the version
of telega-server installed by Guix.

Created by Brett Gilio <brettg@gnu.org>

--- a/telega-server.el
+++ b/telega-server.el
@@ -113,7 +113,6 @@ If already deferring, then just executes the BODY."
 If BUILD-FLAGS is specified, then rebuild server without any
 queries using this flags for building, could be empty string.
 Otherwise query user about building flags."
-  (interactive)
   (telega-test-env 'quiet)
   (when (or build-flags
             (y-or-n-p "Build `telega-server'? "))
@@ -137,11 +136,8 @@ Otherwise query user about building flags."
 (defun telega-server--find-bin ()
   "Find telega-server executable.
 Raise error if not found."
-  (let ((exec-path (cons telega-directory exec-path)))
-    (or (executable-find "telega-server")
-        (progn (telega-server-build)
-               (executable-find "telega-server"))
-        (error "`telega-server' not found in exec-path"))))
+  (or (executable-find "telega-server")
+      (error "`telega-server' not found in exec-path")))
 
 (defun telega-server-version ()
   "Return telega-server version."