perf header: In pipe mode dump features without --header/-I

perf header: In pipe mode dump features without --header/-I

In pipe mode the header features are contained within events. While
other events dump details the header features only dump if --header or
-I are passed, which doesn't make sense as in pipe mode there is no
perf file header. Make the printing of the information conditional on
dump_trace as with other events.

Before:
```
$ perf record -o - -a sleep 1 | perf script -D -i -
...
0x2c8@pipe [0x54]: event: 80
.
. ... raw event: size 84 bytes
.  0000:  50 00 00 00 00 00 54 00 05 00 00 00 00 00 00 00  P.....T.........
.  0010:  40 00 00 00 36 2e 31 35 2e 72 63 37 2e 67 61 64  @...6.15.rc7.gad
.  0020:  32 61 36 39 31 63 39 39 66 62 00 00 00 00 00 00  2a691c99fb......
.  0030:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0040:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0050:  00 00 00 00                                      ....

0 0 0x2c8 [0x54]: PERF_RECORD_FEATURE
```

After:
```
$ perf record -o - -a sleep 1 | perf script -D -i -
...
0x2c8@pipe [0x54]: event: 80
.
. ... raw event: size 84 bytes
.  0000:  50 00 00 00 00 00 54 00 05 00 00 00 00 00 00 00  P.....T.........
.  0010:  40 00 00 00 36 2e 31 35 2e 72 63 37 2e 67 61 64  @...6.15.rc7.gad
.  0020:  32 61 36 39 31 63 39 39 66 62 00 00 00 00 00 00  2a691c99fb......
.  0030:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0040:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
.  0050:  00 00 00 00                                      ....

0 0 0x2c8 [0x54]: PERF_RECORD_FEATURE, # perf version : 6.15.rc7.gad2a691c99fb
```

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250617223356.2752099-4-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>