Update KeepAlive and RemotePF examples

[exceptionfactory]

As requested in issue #784, this pull request updates the KeepAlive example class to set the KeepAlive interval prior to connecting, following the behavior adjustments introduced in SSHJ 0.33.0. The RemotePF example follows the same approach for the Heartbeat setting, and removes the call to Transport.setHeartbeatInterval(), which is no longer defined.

[codecov-commenter]

Codecov Report

Merging #791 (60bf3bd) into master (3de0302) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #791      +/-   ##
============================================
- Coverage     64.75%   64.72%   -0.04%     
+ Complexity     1479     1477       -2     
============================================
  Files           211      211              
  Lines          8660     8660              
  Branches        812      812              
============================================
- Hits           5608     5605       -3     
- Misses         2620     2623       +3     
  Partials        432      432              

Impacted Files	Coverage Δ
src/main/java/net/schmizz/keepalive/KeepAlive.java	74.07% <ø> (ø)
...t/schmizz/sshj/connection/ConnectionException.java	33.33% <0.00%> (-11.12%)	⬇️
...zz/sshj/connection/channel/ChannelInputStream.java	76.92% <0.00%> (-3.08%)	⬇️
...in/java/net/schmizz/sshj/common/SecurityUtils.java	46.87% <0.00%> (-1.05%)	⬇️
.../main/java/net/schmizz/sshj/sftp/PacketReader.java	95.74% <0.00%> (+4.25%)	⬆️

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[jkosternl]

Good addition @exceptionfactory. @hierynomus, can you merge this one in please? I had issues with the examples, as what this PR fixes.