Rewrote for dnf5: Lines with only spaces don't spoil previous cfg option

Original dnf4 test "Scenario: Lines that contain only whitespaces do not
spoil previous config options" uses "config-manager --dump" to verify
the value of the repository configuration option.

In dnf5, the global configuration argument "--dump-repo-config" is used
instead.

dnf-behave-tests/dnf/config.feature

@@ -158,6 +158,26 @@ Scenario: Lines that contain only whitespaces do not spoil previous config optio
    gpgcheck = 1
    """
 
+@dnf5
+@bz1722493
+Scenario: Lines that contain only whitespaces do not spoil previous config options
+  Given I create file "/test/dnf.conf" with
+    # the "empty" line between gpgcheck and baseurl intentionally contains spaces
+    """
+    [main]
+    gpgcheck=0
+
+    [testingrepo]
+    gpgcheck=1
+         
+    baseurl=http://some.url/
+    """
+   When I execute dnf with args "--config={context.dnf.installroot}/test/dnf.conf --dump-repo-config=testingrepo"
+   Then stdout contains lines
+   """
+   gpgcheck = 1
+   """
+
 
 @bz1721091
 Scenario: Dnf can use config file from remote location