pclientd: silly proxy fix workaround

[hdevalence]

Related to #3120, this does a silly quick fix, should be replaced by the generic method described there.

[conorsch]

Building pclientd from this branch, and targeting preview, I'm able to query again:

❯ pcli -n http://localhost:8081 view balance
Scanning blocks from last sync height 0 to latest height 204
[1s] ██████████████████████████████████████████████████     204/204     146/s ETA: 0s
 Account  Amount          
 0        20000gm         
 0        501000test_usd  
 0        100cube         
 0        10000pizza      
 0        1001000penumbra 
 0        20000gn         
 0        8000test_usd    
 0        8000penumbra

&

❯ pcli -n http://localhost:8081 view sync
Scanning blocks from last sync height 212 to latest height 212
[0s] ██████████████████████████████████████████████████       0/0       0/s ETA: 0s

cf. the results posted in #3120 (comment)

[hdevalence]

I updated the guide after testing with Buf Studio. I noticed the following messages from pclientd:

Oct 10 13:27:12.296  INFO penumbra_view::worker: starting client sync
Oct 10 13:27:50.116  WARN hyper::proto::h2: Connection header illegal in HTTP/2: connection
Oct 10 13:28:01.262  WARN hyper::proto::h2: Connection header illegal in HTTP/2: connection
Oct 10 13:28:02.879  WARN hyper::proto::h2: Connection header illegal in HTTP/2: connection

Probably worth investigating at a later point.