fix(service ping): correct endpoint, validate and randomize default interval (#10166)

# Which Problems Are Solved

The production endpoint of the service ping was wrong.
Additionally we discussed in the sprint review, that we could randomize
the default interval to prevent all systems to report data at the very
same time and also require a minimal interval.

# How the Problems Are Solved

- fixed the endpoint
- If the interval is set to @daily (default), we generate a random time
(minute, hour) as a cron format.
- Check if the interval is more than 30min and return an error if not.
- Fixed yaml indent on `ResourceCount`

# Additional Changes

None

# Additional Context

as discussed internally

internal/serviceping/worker_test.go

@@ -1050,3 +1050,77 @@ func TestWorker_Work(t *testing.T) {
 		})
 	}
 }
+
+func Test_parseAndValidateSchedule(t *testing.T) {
+	type args struct {
+		interval string
+	}
+	tests := []struct {
+		name          string
+		args          args
+		wantNextStart time.Time
+		wantNextEnd   time.Time
+		wantErr       error
+	}{
+		{
+			name: "@daily, returns randomized daily schedule",
+			args: args{
+				interval: "@daily",
+			},
+			wantNextStart: time.Now(),
+			wantNextEnd:   time.Now().Add(24 * time.Hour),
+		},
+		{
+			name: "invalid cron expression, returns error",
+			args: args{
+				interval: "invalid cron",
+			},
+			wantErr: zerrors.ThrowInvalidArgument(nil, "SERV-NJqiof", "invalid interval"),
+		},
+		{
+			name: "valid cron expression, returns schedule",
+			args: args{
+				interval: "0 0 * * *",
+			},
+			wantNextStart: nextMidnight(),
+			wantNextEnd:   nextMidnight(),
+		},
+		{
+			name: "valid cron expression (extended syntax), returns schedule",
+			args: args{
+				interval: "@midnight",
+			},
+			wantNextStart: nextMidnight(),
+			wantNextEnd:   nextMidnight(),
+		},
+		{
+			name: "less than minInterval, returns error",
+			args: args{
+				interval: "0/15 * * * *",
+			},
+			wantErr: zerrors.ThrowInvalidArgumentf(nil, "SERV-FJ12", "interval must be at least %s", minInterval),
+		},
+		{
+			name: "less than minInterval (extended syntax), returns error",
+			args: args{
+				interval: "@every 15m",
+			},
+			wantErr: zerrors.ThrowInvalidArgumentf(nil, "SERV-FJ12", "interval must be at least %s", minInterval),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := parseAndValidateSchedule(tt.args.interval)
+			assert.ErrorIs(t, err, tt.wantErr)
+			if tt.wantErr == nil {
+				now := time.Now()
+				assert.WithinRange(t, got.Next(now), tt.wantNextStart, tt.wantNextEnd)
+			}
+		})
+	}
+}
+
+func nextMidnight() time.Time {
+	year, month, day := time.Now().Date()
+	return time.Date(year, month, day+1, 0, 0, 0, 0, time.Local)
+}