read time calculation error in DirectTrinoPageSource

[coderwf]

DirectTrinoPageSource contains server ConnectorPageSource Reader, so it's read time shoud be a value accumulated by all ConnectorPageSource.

Otherwise, a negative relative read time will be calculated out by caller, because the caller in trino accumlates the read time by difference of pre(readtime) and current(readtime), if current ConnectorPageSource changed, it may be return a less read time, it will cause a check non-negative error and calculate incorrection

PR:#82