Enable browser cache when running test server

[fkaelberer]

This PR sets an expiration time of 1 hour for all files that are requested from the test web server, so that javascript sources are not downloaded by the browsers for each pdf file. This reduces the duration of the test significantly, from

All regression tests passed.
Runtime was 881.5 seconds

to

All regression tests passed.
Runtime was 578.2 seconds

The cache expiration time defaults to 0, so that nothing changes unless the expiration time is explicitly set.

I assumed that each browser uses a fresh profile, so that a newly started test doesn't run on old, cached code. Is that always correct?

[Snuffleupagus]

/botio test

[pdfjsbot]

From: Bot.io (Linux)

---

Received

Command cmd_test from @Snuffleupagus received. Current queue size: 0

Live output at: http://107.21.233.14:8877/d53b6bdc73ed317/output.txt

[pdfjsbot]

From: Bot.io (Windows)

---

Received

Command cmd_test from @Snuffleupagus received. Current queue size: 0

Live output at: http://107.22.172.223:8877/8fd6180126bf237/output.txt

[pdfjsbot]

From: Bot.io (Windows)

---

Success

Full output at http://107.22.172.223:8877/8fd6180126bf237/output.txt

Total script time: 23.32 mins

• Font tests: Passed
• Unit tests: Passed
• Regression tests: Passed

[pdfjsbot]

From: Bot.io (Linux)

---

Success

Full output at http://107.21.233.14:8877/d53b6bdc73ed317/output.txt

Total script time: 24.33 mins

• Font tests: Passed
• Unit tests: Passed
• Regression tests: Passed

[fkaelberer]

Hmm, the test bot seems rather unimpressed by this change, but still, Linux test is down to 24 mins from 26 mins in #4861, #4832, #4824, Windows test is down to 23 from 24 minutes.

[timvandermeij]

@yurydelendik Is this good to go?

[yurydelendik]

Thank you