MINOR: [C++] Include <string> before using std::string (#42004)
#38094
| Job | Run time |
|---|---|
| 5m 59s | |
| 1s | |
| 20m 39s | |
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| 50m 8s | |
| 38m 51s | |
| 26m 23s | |
| 36m 30s | |
| 29m 13s | |
| 4h 1m 19s |