mixin: drop the asserts on removed configuration knobs

The networkErrorRateThreshold, networkDiscardRateThreshold,
enableActiveDirectory and enableTime knobs never shipped in a release,
so nothing needs to fail the build on them.

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

contrib/mixin/README.md

@@ -224,11 +224,7 @@ have no `keep_firing_for` and resolve as soon as their condition clears.
 older servers.
 
 The network error and discard thresholds are percentages of all packets on the
-interface. Earlier versions of the mixin had `networkErrorRateThreshold` and
-`networkDiscardRateThreshold` in packets per second; setting them now fails
-the build with a message that names the replacements. The same goes for
-`enableActiveDirectory` and `enableTime`, replaced by `collectors+: { ad: true }`
-and `collectors+: { time: true }`.
+interface.
 
 `criticalSeverity` defaults to `critical` and `infoSeverity` to `info`; override
 them to match your routing labels. Below the critical disk threshold, both disk

contrib/mixin/alerts/alerts.libsonnet

@@ -6,10 +6,6 @@
   local known = std.objectFields((import '../config.libsonnet')._config.alerts),
   local unknown = std.setDiff(std.set(std.objectFields(c.alerts)), std.set(known)),
   assert std.length(unknown) == 0 : 'Unknown alerts in _config.alerts: ' + std.join(', ', unknown),
-  assert !std.objectHas(c, 'networkErrorRateThreshold') && !std.objectHas(c, 'networkDiscardRateThreshold') :
-         'networkErrorRateThreshold and networkDiscardRateThreshold (packets per second) were replaced by networkErrorRatioThreshold and networkDiscardRatioThreshold (percent of all packets)',
-  assert !std.objectHas(c, 'enableActiveDirectory') && !std.objectHas(c, 'enableTime') :
-         'enableActiveDirectory and enableTime were replaced by collectors+: { ad: true } and collectors+: { time: true }',
 }
 + (import 'exporter.libsonnet')
 + (import 'cpu.libsonnet')