Web UI .js files code ignores -ui-content-path flag

#### Overview of the Issue

I noticed that Web UI of Consul v1.9.3 generates .js files which ignore `-ui-content-path` flag. I checked the latest Consul code and it seems that it has a hardcoded `GET /v1/...` HTTP requests as well. I have to use `sub_filter` rules of my Nginx reverse proxy to fix the invalid requests.

#### Reproduction Steps

Steps to reproduce this issue:

1. Create a cluster with 3 nodes using `-ui` and `-ui-content-path /foo/ui/` flags for them
2. Configure Nginx reverse proxy for handling the cluster, e.g.:
```
upstream foo_consul_backend {
server consul1.foo.example.com:8500;
server consul2.foo.example.com:8500;
server consul3.foo.example.com:8500;
}

server {
listen 443;
server_name consul.example.com;

ssl on;
ssl_certificate /etc/letsencrypt/live/consul.example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/consul.example.com/privkey.pem;

access_log /var/log/nginx/consul-access-ssl.log;
error_log /var/log/nginx/consul-error-ssl.log;

location / {
root /var/www/html/consul/;
index index.html;
}

location /foo/ui/ {
proxy_set_header Accept-Encoding "";
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://foo_consul_backend/foo/ui/;
}
location /foo/v1/ {
proxy_pass http://foo_consul_backend/v1/;
}
```
3. Go to https://consul.example.com/foo/ui/ using your favourite web browser
4. See an empty page

### Consul info for Server

Server info

```
agent:
check_monitors = 1
check_ttls = 0
checks = 1
services = 0
build:
prerelease =
revision = f55da930
version = 1.9.3
consul:
acl = disabled
bootstrap = false
known_datacenters = 1
leader = false
leader_addr = 10.10.10.15:8300
server = true
raft:
applied_index = 774
commit_index = 774
fsm_pending = 0
last_contact = 84.006927ms
last_log_index = 774
last_log_term = 2
last_snapshot_index = 0
last_snapshot_term = 0
latest_configuration = [{Suffrage:Voter ID:24796312-70d4-4cb4-b7b6-558ca82edecb Address:10.10.10.13:8300} {Suffrage:Voter ID:7c50b85e-0389-4408-986d-5a0162f52f2e Address:10.10.10.14:8300} {Suffrage:Voter ID:e94eaff8-43de-4533-9f41-13ae882abf49 Address:10.10.10.15:8300}]
latest_configuration_index = 0
num_peers = 2
protocol_version = 3
protocol_version_max = 3
protocol_version_min = 0
snapshot_version_max = 1
snapshot_version_min = 0
state = Follower
term = 2
runtime:
arch = amd64
cpu_count = 16
goroutines = 103
max_procs = 16
os = linux
version = go1.15.6
serf_lan:
coordinate_resets = 0
encrypted = true
event_queue = 0
event_time = 2
failed = 0
health_score = 0
intent_queue = 0
left = 0
member_time = 19
members = 9
query_queue = 0
query_time = 1
serf_wan:
coordinate_resets = 0
encrypted = true
event_queue = 0
event_time = 1
failed = 0
health_score = 0
intent_queue = 0
left = 0
member_time = 4
members = 3
query_queue = 0
query_time = 1
```

### Operating system and Environment details

Debian GNU/Linux 10.9, amd64

### Log Fragments

Below a piece of Nginx logs:
```
11.22.33.44 - - [10/Jun/2021:07:26:30 +0000] "GET /foo/ui/ HTTP/1.1" 200 3429 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:88.0) Gecko/20100101 Firefox/88.0" "-"
11.22.33.44 - - [10/Jun/2021:07:26:37 +0000] "GET /v1/catalog/datacenters HTTP/1.1" 404 136 "https://consul.example.com/foo/ui/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:88.0) Gecko/20100101 Firefox/88.0" "-"
```
and an error log in my Firefox web developer console:
```
Error while processing route: index The adapter could not find the resource r@https://consul.example.com/foo/ui/assets/vendor-4f6b2352943214ccc7e7113ab286a174.js:6280:19
r@https://consul.example.com/foo/ui/assets/vendor-4f6b2352943214ccc7e7113ab286a174.js:6284:54
value@https://consul.example.com/foo/ui/assets/consul-ui-ee55527e9defc2d4261720f39a9f7525.js:131:12
value/<@https://consul.example.com/foo/ui/assets/consul-ui-ee55527e9defc2d4261720f39a9f7525.js:123:158
promise callback*value@https://consul.example.com/foo/ui/assets/consul-ui-ee55527e9defc2d4261720f39a9f7525.js:123:130
j@https://consul.example.com/foo/ui/assets/consul-ui-ee55527e9defc2d4261720f39a9f7525.js:112:10
value@https://consul.example.com/foo/ui/assets/consul-ui-ee55527e9defc2d4261720f39a9f7525.js:139:139
tt

Start by locating the Web UI source that produces requests such as GET /v1/catalog/datacenters and the handling of -ui-content-path. Reproduce the issue with the /foo/ui/ configuration and inspect consul-ui-ee55527e9defc2d4261720f39a9f7525.js; done means Web UI API requests include the configured path without Nginx sub_filter rules.

Written by the indexing model from the issue text.