chore(ci): run tests as step after building CLI instead of separate flow

This will reduce our CI usage by building Topola one time less. This is
needed because it turned out that we are straining the CI and were asked
to reduce our footprint:

https://codeberg.org/topola/topola/issues/155

.woodpecker/build_cli_then_test.yaml

@@ -20,3 +20,14 @@ steps:
       - cargo build -p topola-cli --no-default-features --features "$FEATURES" --
     when:
       event: [pull_request, push, tag]
+
+  # Testing is a step instead of a separate flow to reduce Codeberg's CI usage.
+  test:
+    image: rust
+    environment:
+      RUST_BACKTRACE: 1
+      CARGO_TERM_COLOR: always
+    commands:
+      # Only run tests for stable channel to avoid straining Codeberg's CI.
+      - test "$CHANNEL" = "stable"
+      - cargo test --verbose --no-default-features --features "$FEATURES"

.woodpecker/test.yaml

@@ -1,22 +0,0 @@
-# SPDX-FileCopyrightText: 2024 Topola contributors
-#
-# SPDX-License-Identifier: MIT
-
-matrix:
-  include:
-    - CHANNEL: stable
-      FEATURES: disable_contracts
-    #- CHANNEL: nightly
-      #FEATURES:
-
-steps:
-  test:
-    image: rust
-    environment:
-      RUST_BACKTRACE: 1
-      CARGO_TERM_COLOR: always
-    commands:
-      - rustup default "$CHANNEL"
-      - cargo test --verbose --no-default-features --features "$FEATURES"
-    when:
-      event: [pull_request, push, tag]