fix upstream appendheader to upstream query string lost

[champly]

Issues associated with this PR

#1030

config

"listeners":[
    {
        "name":"serverListener",
        "address": "127.0.0.1:2046",
        "bind_port": true,
        "filter_chains": [{
            "filters": [
                {
                    "type": "proxy",
                    "config": {
                        "downstream_protocol": "Http2",
                        "upstream_protocol": "Http1",
                        "router_config_name":"server_router"
                    }
                }
            ]
        }]
    },
    {
        "name":"clientListener",
        "address": "127.0.0.1:2045",
        "bind_port": true,
        "filter_chains": [{
            "filters": [
                {
                    "type": "proxy",
                    "config": {
                        "downstream_protocol": "Http1",
                        "upstream_protocol": "Http2",
                        "router_config_name":"client_router"
                    }
                }
            ]
        }]
    }
]

request

if curl "http://localhost:2045/aabb?aa=123" mosn will be return 400 http code, and print parse query parameters error,parameters = %!(EXTRA string=aa=123)

solution

upstream's AppendHeaders function format URI error, because lost query placeholder.

[codecov-io]

Codecov Report

Merging #1077 into master will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1077      +/-   ##
==========================================
+ Coverage   56.04%   56.07%   +0.03%     
==========================================
  Files         246      246              
  Lines       23073    23073              
==========================================
+ Hits        12931    12939       +8     
+ Misses       8980     8973       -7     
+ Partials     1162     1161       -1     

Impacted Files	Coverage Δ
pkg/network/connection.go	34.97% <0.00%> (-0.38%)	⬇️
pkg/module/http2/transport.go	78.47% <0.00%> (+0.14%)	⬆️
pkg/module/http2/server.go	82.36% <0.00%> (+0.58%)	⬆️

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[taoyuanyuan]

thx LGTM