Use port 4318 for otlp*http client default

[MrAlias]

As per the specification and the collector defaults, use port 4318 as the default for HTTP communication.

Fix #2614

[codecov]

Codecov Report

Merging #2625 (0affa8a) into main (94b1848) will increase coverage by 0.0%.
The diff coverage is 90.9%.

@@          Coverage Diff          @@
##            main   #2625   +/-   ##
=====================================
  Coverage   76.1%   76.2%           
=====================================
  Files        173     173           
  Lines      12227   12249   +22     
=====================================
+ Hits        9315    9337   +22     
+ Misses      2669    2665    -4     
- Partials     243     247    +4     

Impacted Files	Coverage Δ
...ers/otlp/otlpmetric/internal/otlpconfig/options.go	80.2% <88.4%> (+4.2%)	⬆️
...ters/otlp/otlptrace/internal/otlpconfig/options.go	80.2% <88.4%> (+4.2%)	⬆️
exporters/otlp/otlpmetric/otlpmetrichttp/client.go	76.7% <100.0%> (-2.1%)	⬇️
...xporters/otlp/otlpmetric/otlpmetrichttp/options.go	72.9% <100.0%> (+2.3%)	⬆️
exporters/otlp/otlptrace/otlptracehttp/client.go	81.7% <100.0%> (-1.6%)	⬇️
exporters/otlp/otlptrace/otlptracehttp/options.go	100.0% <100.0%> (ø)
exporters/jaeger/jaeger.go	92.6% <0.0%> (-0.9%)	⬇️
... and 1 more