Getting ESO headers fails to retrieve keyword values which include a /

Code tries to figure out the comment splitting on / leaving out the right part reading ESO headers. But keyword values are truncated before / when it includes one or more in its value.

The output of next python code snippet should provide the full instrument name with a revision ID on top of next input values:
```
HIERARCH ESO INS ID = 'GRAVITY/176642' / Instrument ID.
HIERARCH ESO INS ID = 'PIONIER/$Revision: 350678 $' / Instrument ID.
```

```python
from astroquery.eso.core import EsoClass
eso = EsoClass()
headers = eso.get_headers(["GRAVI.2024-09-27T07:22:10.935","PIONI.2024-01-12T08:55:01.576"])
print(headers["HIERARCH ESO INS ID"])
```

At present time, the output is :
```
HIERARCH ESO INS ID
-------------------
GRAVIT
PIONIE
```

If this is a bug, I guess that a fix should also manage multiple quotes occurences with and without escaping and maybe other tricky cases ...

Start by reproducing the example through astroquery.eso.core.EsoClass.get_headers and inspect the ESO header parsing it invokes. Verify that values such as 'GRAVITY/176642' and 'PIONIER/$Revision: 350678 $' are returned in full, including the slash, and check the related parsing behavior for quoted values.

Written by the indexing model from the issue text.