Fix Brave Ads cppclean warning about dangling ptr

[tmancey]

No description provided.

[btlechowski]

Verification passed on

Brave	1.43.63 Chromium: 104.0.5112.81 (Official Build) beta (64-bit)
Revision	5b7b76419d50f583022568b6764b630f6ddc9208-refs/branch-heads/5112@{#1309}
OS	Ubuntu 18.04 LTS VM

Verified test plan from brave/brave-core#14194

notification ad

Verified conversion was triggered

[4158:4158:0816/224506.898557:VERBOSE1:conversions.cc(355)] Conversion for ad_notification with campaign id ab296d81-7095-4898-b293-3b1f9e135412, creative set id db0ce093-e886-46c7-929a-6a5a31da3a8d, creative instance id 6cd435fc-aa2c-4954-8f75-e216c71559d5 and advertiser id 8fc94bb9-2ab3-49df-a5a7-8ee680384dec
[4158:4158:0816/224506.910924:VERBOSE1:conversions.cc(342)] There was a conversion match
[4158:4158:0816/224506.921889:VERBOSE6:conversions.cc(405)] Successfully logged conversion event
[4158:4158:0816/224506.934850:VERBOSE3:conversions.cc(429)] Successfully appended conversion to queue
[4158:4158:0816/224506.941719:VERBOSE1:conversions.cc(572)] Convert ad_notification with campaign id ab296d81-7095-4898-b293-3b1f9e135412, creative set id db0ce093-e886-46c7-929a-6a5a31da3a8d, creative instance id 6cd435fc-aa2c-4954-8f75-e216c71559d5 and advertiser id 8fc94bb9-2ab3-49df-a5a7-8ee680384dec in 5 hours, 21 minutes, 47 seconds at 04:06:53.894

Verified the id is extracted for the conversion

Verified conversion was successful

[5115:5115:0817/225035.266192:VERBOSE1:redeem_unblinded_token.cc(358)] Successfully redeemed unblinded token for ad_notification with confirmation id 00eeed53-c83d-4ed5-830b-51773b55549c, transaction id 23a96573-ec38-4677-9233-dda8bab9e68e, creative instance id 6cd435fc-aa2c-4954-8f75-e216c71559d5 and conversion

Verified envelop was present